Chapter VI: Introduction: To Part I (2)

The most abundant and possibly the most important organisms that may be considered as benefactors to the Spongillidæ are the green corpuscles that live in the cells of certain species (fig. 2, p. 31), notably _Spongilla lacustris_, _S. proliferens_, and _Dosilia plumosa_. I have already said that these bodies are in all probability algæ which live free in the water and move actively at one stage of their existence, but some of them are handed on directly from a sponge to its descendants in the cells of the gemmule. In their quiescent stage they have been studied by several zoologists, notably by Sir Ray Lankester[Q] and Dr. W. Weltner[R], but the strongest light that has been cast on their origin is given by the researches of Dr. F. W. Gamble and Mr. F. Keeble (Q. J. Microsc. Sci. London, xlvii, p. 363, 1904, and li, p. 167, 1907). These researches do not refer directly to the Spongillidæ but to a little flat-worm that lives in the sea, _Convoluta roscoffiensis_. The green corpuscles of this worm so closely resemble those of _Spongilla_ that we are justified in supposing a similarity of origin. It has been shown by the authors cited that the green corpuscles of the worm are at one stage minute free-living organisms provided at one end with four flagella and at the other with a red pigment spot. The investigators are of the opinion that these organisms exhibit the essential characters of the algæ known as Chlamydomonadæ, and that after they have entered the worm they play for it the part of an excretory system.

[Footnote Q: Q. J. Microsc. Sci. London, xxii. p. 229
(1882).]

[Footnote R: Arch. Naturg. Berlin, lix (i), p. 260 (1893).]

As they exist in the cells of _Spongilla_ the corpuscles are minute oval bodies of a bright green colour and each containing a highly refractile colourless granule. A considerable number may be present in a single cell. It is found in European sponges that they lose their green colour if the sponge is not exposed to bright sunlight. In India, however, where the light is stronger, this is not always the case. Even when the colour goes, the corpuscles can still be distinguished as pale images of their green embodiment. They are called _Chlorella_ by botanists, who have studied their life-history but have not yet discovered the full cycle. See Beyerinck in the Botan. Zeitung for 1890 (vol. xlviii, p. 730, pl. vii; Leipzig), and for further references West's 'British Freshwater Algæ,' p. 230 (1904).

The list of beneficent organisms less commonly present than the green corpuscles includes a _Chironomus_ larva that builds parchment-like tubes in the substance of _Spongilla carteri_ and so assists in supporting the sponge, and of a peculiar little worm (_Chætogaster spongillæ_[S]) that appears to assist in cleaning up the skeleton of the same sponge at the approach of the hot weather and in setting free the gemmules (p. 93).

[Footnote S: Journ. As. Soc. Beng. n. s. ii, 1906, p. 189.]

(c) _Organisms that take shelter in the Sponge or adhere to it externally._

There are many animals which take shelter in the cavities of the sponge without apparently assisting it in any way. Among these are the little fish _Gobius alcockii_, which lays its eggs inside the oscula of _S. carteri_, thus ensuring not only protection but also a proper supply of oxygen for them (p. 94); the molluscs (_Corbula_, spp.) found inside _S. alba_ var. _bengalensis_ (p. 78); and the Isopod (_Tachæa spongillicola_) that makes its way into the oscula of _Spongilla carteri_ and _S. crateriformis_ (pp. 86, 94).

In Europe a peculiar ciliated Protozoon (_Trichodina spongillæ_) is found attached to the external surface of freshwater sponges. I have noticed a similar species at Igatpuri on _Spongilla crateriformis_, but it has not yet been identified. It probably has no effect, good or bad, on the sponge.

FRESHWATER SPONGES IN RELATION TO MAN.

In dealing with _Spongilla carteri_ I have suggested that sponges may be of some hygienic importance in absorbing putrid organic matter from water used both for ablutionary and for drinking purposes, as is so commonly the case with regard to ponds in India. Their bad odour has caused some species of Spongillidæ to be regarded as capable of polluting water, but a mere bad odour does not necessarily imply that they are insanitary.

Unless my suggestion that sponges purify water used for drinking purposes by absorbing putrid matter should prove to be supported by fact, the Spongillidæ cannot be said to be of any practical benefit to man. The only harm that has been imputed to them is that of polluting water[T], of blocking up water-pipes by their growth--a very rare occurrence,--and of causing irritation to the human skin by means of their spicules--a still rarer one. At least one instance is, however, reported in which men digging in a place where a pond had once been were attacked by a troublesome rash probably due to the presence of sponge-spicules in the earth, and students of the freshwater sponges should be careful not to rub their eyes after handling dried specimens.

[Footnote T: See Potts, Proc. Ac. Philad. 1884, p. 28.]

INDIAN SPONGILLIDÆ COMPARED WITH THOSE OF OTHER COUNTRIES.

In Weltner's catalogue of the freshwater sponges (1895) seventy-six recent species of Spongillidæ (excluding _Lubosmirskia_) are enumerated, and the number now known is well over a hundred. In India we have twenty-nine species, subspecies, and varieties, while from the whole of Europe only about a dozen are known. In the neighbourhood of Calcutta nine species, representing three genera and a subgenus, have been found; all of them occur in the Museum tank. The only other region of similar extent that can compare with India as regards the richness of its freshwater sponge fauna is that of the Amazon, from which about twenty species are known. From the whole of North America, which has probably been better explored than any other continent so far as Spongillidæ are concerned, only twenty-seven or twenty-eight species have been recorded.

The Indian species fall into seven genera, one of which (_Spongilla_) consists of three subgenera. With one exception (that of _Pectispongilla_, which has only been found in Southern India) these genera have a wide distribution over the earth's surface, and this is also the case as regards the subgenera of Spongilla. Four genera (_Heteromeyenia_, _Acalle_, _Parmula_, and _Uruguaya_) that have not yet been found in India are known to exist elsewhere.

Five of the Indian species are known to occur in Europe, viz., _Spongilla lacustris_, _S. crateriformis_, _S. carteri_, _S. fragilis_, _Trochospongilla pennsylvanica_; while _Ephydatia meyeni_ is intermediate between the two commonest representatives of its genus in the Holarctic Zone, _Ephydatia fluviatilis_ and _E. mülleri_. Of the species that occur both in India and in Europe, two (_Spongilla lacustris_ and _S. fragilis_) are found in this country in forms sufficiently distinct to be regarded as subspecies or local races. Perhaps this course should also be taken as regards the Indian forms of _S. carteri_, of which, however, the commonest of the Indian races would be the typical one; but _S. crateriformis_ and _T. pennsylvanica_ seem to preserve their specific characters free from modification, whether they are found in Europe, Asia, or America.

The freshwater sponges of Africa have been comparatively little studied, but two Indian species have been discovered, _S. bombayensis_ in Natal and _S. alba_ var. _cerebellata_ in Egypt. Several of the species from the Malabar Zone are, moreover, closely allied to African forms (p. 11).

FOSSIL SPONGILLIDÆ.

The Spongillidæ are an ancient family. Young described a species (_Spongilla purbeckensis_) from the Upper Jurassic of Dorset (Geol. Mag. London (new series) v, p. 220 (1878)), while spicules, assigned by Ehrenberg to various genera but actually those of _Spongilla lacustris_ or allied forms, have been found in the Miocene of Bohemia (see Ehrenberg's 'Atlas für Micro-Geologie,' pl. xi (Leipzig, 1854), and Traxler in Földt. Közl., Budapest, 1895, p. 211). _Ephydatia_ is also known in a fossil condition, but is probably less ancient than _Spongilla_.

Ehrenberg found many sponge spicules in earth from various parts of the Indian Empire (including Baluchistan, Mangalore, Calcutta, the Nicobars and Nepal) and elsewhere, and it might be possible to guess at the identity of some of the more conspicuous species figured in his 'Atlas.' The identification of sponges from isolated spicules is, however, always a matter of doubt, and in some cases Ehrenberg probably assigned spicules belonging to entirely different families or even orders to the same genus, while he frequently attributed the different spicules of the same species to different genera. Among his fossil (or supposed fossil) genera that may be assigned to the Spongillidæ wholly or in part are _Aphidiscus_, _Spongolithis_, _Lithastericus_ and _Lithosphæridium_, many of the species of these "genera" certainly belonging to _Spongilla_ and _Ephydatia_.

ORIENTAL SPONGILLIDÆ NOT YET FOUND IN INDIA.

Few freshwater sponges that have not been found in India are as yet known from the Oriental Region, and there is positive as well as negative evidence that Spongillidæ are less abundant in Malaysia than in this country. The following list includes the names of those that have been found, with notes regarding each species. It is quite possible that any one of them may be found at any time within the geographical boundaries laid down for this 'Fauna.' I have examined types or co-types in all cases except that of _Ephydatia fortis_, Weltner.

I. _Spongilla_ (_Euspongilla_) _microsclerifera_*, Annandale (Philippines). P. U.S. Mus. xxxvii, p. 131 (1909).

This sponge is closely related to _S. lacustris_, but apparently does not produce branches. It is remarkable for the enormous number of microscleres in its parenchyma.

II. _S._ (_Euspongilla_) _philippinensis_*, Annandale (Philippines). P. U.S. Mus. xxxvi, p. 629 (1909).

Related to _S. alba_ and still more closely to _S. sceptrioides_ of Australia. From the former it is readily distinguished by having minutely spined megascleres, green corpuscles, slender gemmule-spicules with short spines and no free microscleres.

III. _S._ (? _Euspongilla_) _yunnanensis_*, Annandale (W. China). Rec. Ind. Mus. v, p. 197 (1910).

Apparently allied to _S. philippinensis_ but with smooth skeleton-spicules and a more delicate skeleton.

IV. _S._ (_Stratospongilla_) _sinensis_*, Annandale (Foochow, China). P. U.S. Mus. xxxviii, p. 183 (1910).

This species and _S. clementis_ are referred to _Stratospongilla_ with some doubt. Their gemmules are intermediate in structure between those of that subgenus and those of _Euspongilla_. In _S. sinensis_ the gemmules are packed together in groups at the base of the sponge, and their spicules are smooth, stout, and gradually pointed.

V. _S._ (_Stratospongilla_) _clementis_*, Annandale (Philippines). P. U.S. Mus. xxxvi, p. 631 (1909).

The gemmules are single and closely adherent at the base of the sponge. Their spicules are very slender and minutely spined.

VI. _S._ (? _Stratospongilla_) _coggini_*, Annandale (W. China). Rec. Ind. Mus. v, p. 198 (1910).

The gemmules apparently lack microscleres. They resemble those of _S. clementis_, to which the species is probably related, in other respects. The skeleton-spicules are spiny and rather stout, the species being strongly developed at the two ends.

VII. _S._ (_Stratospongilla_) _sumatrana_*, Weber (Malay Archipelago). Zool. Ergebnisse einer Reise in Niederländisch Ost-Indien, i. p. 38 (1890).

Closely allied to _S. indica_ (p. 100) but with pointed skeleton-spicules.

VIII. _Ephydatia fortis_, Weltner (Philippines). Arch. Naturgesch. lxi(i), p. 141 (1895).

This species is remarkable for the great development of the spines on the shaft of the gemmule-spicules.

IX. _Ephydatia bogorensis_*, Weber (Malay Archipelago). Zool. Ergebnisse einer Reise in Niederländisch Ost-Indien, i, p. 33 (1890).

The gemmule-spicules have rather narrow flattish disks, the edge of which is feebly but closely serrated.

X. _E. blembingia_*, Evans (Malay Peninsula). Q. J. Microsc. Sci. London, xliv, p. 81 (1901).

The gemmules resemble those of _Dosilia plumosa_ but are spherical. There are no free microscleres.

XI. _Tubella vesparium_*, v. Martens (Borneo). Arch. Naturg.

Berlin, xxxiv, p. 62 (1868).

Closely related to _T. vesparioides_ (p. 189), but with spiny megascleres.

As regards _Spongilla decipiens_*, Weber, from the Malay Archipelago, see p. 97.

II.

HISTORY OF THE STUDY OF FRESHWATER SPONGES.

The bath-sponge was known to the Greeks at an early date, and Homer refers to it as being used for cleansing furniture, for expunging writing, and for ablutionary purposes. He also mentions its peculiar structure, "with many holes." "Many things besides," wrote the English naturalist Ray in his 'Historia Plantarum' (1686), "regarding the powers and uses of sponges have the Ancients: to them refer." Ray himself describes at least one freshwater species, which had been found in an English river, and refers to what may be another as having been brought from America. In the eighteenth century Linné, Pallas and other authors described the commoner European Spongillidæ in general terms, sometimes as plants and sometimes as animals, more usually as zoophytes or "plant-animals" partaking of the nature of both kingdoms. The gemmules were noted and referred to as seeds. The early naturalists of the Linnæan Epoch, however, added little to the general knowledge of the Spongillidæ, being occupied with theory in which theological disputes were involved rather than actual observation, and, notwithstanding the fact that the animal nature of sponges was clearly demonstrated by Ellis[U] in 1765, it was not until the nineteenth century was well advanced that zoologists could regard sponges in anything like an impartial manner.

[Footnote U: Phil. Trans. Roy. Soc. lv, p. 280.]

One of the pioneers in the scientific study of the freshwater forms was the late Dr. H. J. Carter, who commenced his investigations, and carried out a great part of them, in Bombay with little of the apparatus now considered necessary, and with a microscope that must have been grossly defective according to modern ideas. His long series of papers (1848-1887) published in the 'Annals and Magazine of Natural History' is an enduring monument to Indian zoology, and forms the best possible introduction to the study of the Spongillidæ. Even his earlier mistakes are instructive, for they are due not so much to actual errors in observation as to a faithful transcription of what was observed with faulty apparatus.

Contemporary with Carter were two authors whose monographs on the freshwater sponges did much to advance the study of the group, namely, J. S. Bowerbank, whose account of the species known at the time was published in the 'Proceedings of the Zoological Society of London' in 1882, and the veteran American naturalist Mr. Edward Potts, whose study of the freshwater sponges culminated in his monograph published in the 'Proceedings of the Academy of Natural Sciences of Philadelphia' in 1887. Carter's own revision of the group was published in the 'Annals and Magazine of Natural History' in 1881. The names of Vejdovsky, who prefaced Potts's monograph with an account of the European species, and of Dybowsky, who published several important papers on classification, should also be mentioned, while Weltner's catalogue of the known species (1895) is of the greatest possible value to students of the group.

Many authors have dealt with the physiology, reproduction and development of the Spongillidæ, especially in recent years; Dr. R. Evans's description of the larva of _Spongilla lacustris_ (1899), and his account of the development of the gemmule in _Ephydatia blembingia_ (1901), Zykoff's account of the development of the gemmule and of the sponge from the gemmule (1892), and Weltner's observations on colour and other points (1893, 1907), may be mentioned in particular. Laurent's observations on development (1844), which were published in the 'Voyage de la Bonite,' and especially the exquisite plates which accompany them, have not received the notice they deserve, probably on account of their method of publication.

LITERATURE.

The fullest account of the literature on the Spongillidæ as yet published will be found in the first of Weltner's 'Spongillidenstudien' (Archiv für Naturgeschichte, lix (i), p. 209, 1893). Unfortunately it contains no references of later date than 1892. The following list is not a complete bibliography, but merely a list of books and papers that should prove of use to students of the Oriental Spongillidæ.

(a) _Works of Reference._

1863. BOWERBANK, "A Monograph of the Spongillidæ," P. Zool. Soc. London, 1863, pp. 440-472, pl. xxxviii.

1867. GRAY, J. E., "Notes on the arrangement of Sponges, with the description of some new genera." _ibid._ 1867, pp. 492-558.

1881. CARTER, "History and classification of the known species of _Spongilla_," Ann. Nat. Hist. (5) vii, pp. 77-107, pls. v, vi.

1883. VEJDOVSKY, "Die Süsswasserschwämme Böhmens," Abh. Kön. Böhm. Ges. Wiss. (math.-natur. Classe), xii, pp. 1-43, pls. i-iii.

1887. VOSMAER, "Spongien (Porifera)," in Bronn's Thier-Reichs.

1887. POTTS, "Contributions towards a synopsis of the American forms of Fresh-Water Sponges, with descriptions of those named by other authors and from all parts of the world," P. Ac. Philad. pp. 158-279, pls. v-xii.

1887. VEJDOVSKY, "Diagnosis of the European Spongillidæ," _ibid._ pp. 172-180.

1888. WIERZEJSKI, "Beitrag zur Kenntnis der Süsswasserschwämme," Verh. k.-k. zool.-bot. Ges. Wien, xxxviii, pp. 529-536, pl. xii.

1891. WELTNER, in Zacharias's Die Tier- und Pflanzenwelt des Süsswassers: I, Die Süsswasserschwämme.

1895. WELTNER, "Spongillidenstudien, III," Arch. Naturg. Berlin, lxi (i), pp. 114-144.

1895. KORSCHELT and HEIDER, Text-book of the Embryology of Invertebrates: English edition, prepared by E. L. Mark and W. McM. Woodworth, Vol. I, chap. i.

1900. MINCHIN, Sponges--Phylum Porifera in Lankester's "Treatise on Zoology," ii.

1905. KÜKENTHAL, W., Leitfaden für das Zoologische Praktikum (3rd Ed., Jena), 2. Kursus: Porifera, Schwämme, p. 31.

1906. SOLLAS, I. B. J., Cambridge Natural History--I. Porifera (Sponges).

1909. WELTNER, "Spongillidæ, Süsswasserschwämme," in Brauer's "Die Süsswasserfauna Deutschlands," Heft xix, pp. 177-190.

1910. LLOYD, An Introduction to Biology for Students in India.

(b) _Special Memoirs on Anatomy, Physiology, and Development._

1844. LAURENT, "Recherches sur l'Hydre et l'Eponge d'eau douce," Voyage de la Bonite, ii, pp. 113-276.

1854. CARTER, "Zoosperms in _Spongilla_," Ann. Nat. Hist. (2) xiv, pp. 334-336, pl. xi, figs. 1-6.

1857. CARTER, "On the ultimate structure of _Spongilla_, and additional notes on Freshwater Infusoria," Ann. Nat. Hist. (2) xx, pp. 21-41, pl. i, figs. 1-11.

1859. CARTER, "On the identity in structure and composition of the so-called 'seed-like body' of _Spongilla_ with the winter-egg of the Bryozoa, and the presence of starch-granules in each," Ann. Nat. Hist. (3) iii, pp. 331-343, pl. viii.

1859. LIEBERKÜHN, "Neue Beiträge zur Anatomie der Spongien," Arch. Anat. Phys. J. Müller, pp. 374-375, 526-528.

1871. CARTER, "Discovery of the animal of the Spongiadæ confirmed," Ann. Nat. Hist. (4) vii, p. 445.

1871. HAECKEL, "Ueber die sexuelle Fortpflanzung und das natürliche System der Schwämme," Jenaische Zeitschr. f. Naturw. vi, pp. 643, 645.

1874. CARTER, "On the nature of the seed-like body of _Spongilla_; on the origin of the mother-cell of the spicule; and on the presence of spermatozoa in the _Spongida_," Ann. Nat. Hist. (4) xiv, pp. 97-111.

1874. LANKESTER, E. RAY, "The mode of occurrence of chlorophyll in _Spongilla_," Q. J. Micr. Sci. xiv, pp. 400-401.

1875. SORBY, H., "On the Chromatological relations of _Spongilla fluviatilis_," Q. J. Micr. Sci. xv, pp. 47-52.

1878. GANIN, "Zur Entwickelung der _Spongilla fluviatilis_," Zool. Anz. I, pp. 195-199.

1882. CARTER, "Spermatozoa, polygonal cell-structure, and the green colour in _Spongilla_, together with a new species," Ann. Nat. Hist. (5) x, pp. 362-372, pl. 16.

1882. GEDDES, "Further researches on animals containing chlorophyll," Nature, xxv, pp. 303-305, 361-362.

1882. LANKESTER, E. RAY, "On the chlorophyll-corpuscles and amyloid deposits of _Spongilla_ and _Hydra_," Q. J. Micr. Sci. xxii (n. s.), pp. 229-254, pl. xx.

1883. MARSHALL, W., "Einige vorläutige Bemerkungen über die Gemmulä der Süsswasserschwämme," Zool. Anz. vi, pp. 630-634, 648-652.

1884. CARTER, "The branched and unbranched forms of the Freshwater Sponges considered generally," Ann. Nat. Hist. (5) xiii, pp. 269-273.

1884. MARSHALL, W., "Vorläutige Bemerkungen über die Fortpflanzungsverhältnisse von _Spongilla lacustris_," Ber. Naturf. Ges. Leipzig,* pp. 22-29.

1884. POTTS, "Freshwater Sponges as improbable causes of the pollution of river-water," P. Ac. Philad. pp. 28-30.

1885. SCHULZE, F. E., "Über das Verhältniss der Spongien zu den Choanoflagellaten," SB. preuss. Akad. Wiss. Berlin, pp. 179-191.

1886. GOETTE, Untersuchungen zur Entwickelungsgeschichte von _Spongilla fluviatilis_*, Hamburg und Leipzig (5 plates).

1886. WIERZEJSKI, "Le développement des Gemmules des Eponges d'eau douce d'Europe," Arch. Slaves Biologie, i, pp. 26-47 (1 plate).

1887. CARTER, "On the reproductive elements of the _Spongida_," Ann. Nat. Hist. (5) xix, pp. 350-360.

1889. MAAS, "Zur Metamorphose der Spongillalarve," Zool. Anz. xii, pp. 483-487.

1890. MAAS, "Ueber die Entwickelung des Süsswasserschwämmes," Zeitschr. Wiss. Zool. 1, pp. 527-554, pls. xxii, xxiii.

1890. WEBER, M. et Mme. A., "Quelques nouveau cas de Symbiose," Zool. Ergebn. einer Reise Niederländ. Ost-Indien, i, pp. 48-72, pl. v.

1892. ZYKOFF, "Die Entwicklung der Gemmulä der _Ephydatia fluviatilis_ auct.," Zool. Anz. xv, pp. 95-96.

1892. ZYKOFF, "Die Bildung der Gemmulä bei _Ephydatia Fluviatilis_," Revue Sc. Nat. Soc. St. Pétersbourg,* pp. 342-344.

1892. ZYKOFF, "Die Entwicklung der Gemmulä bei _Ephydatia fluviatilis_ auct.," Bull. Soc. Imp. Natur. Moscou, n. s. vi, pp. 1-16, pl. i, ii.

1892. ZYKOFF, "Entwickelungsgeschichte von _Ephydatia mülleri_, Liebk. aus den Gemmulæ," Biol. Centralbl. xii, pp. 713-716.

1893. WELTNER, "Spongillidenstudien, II," Arch. Naturg. Berlin, lix (1), pp. 245-282, pls. viii, ix.

1899. EVANS, R., "The structure and metamorphosis of the larva of _Spongilla lacustris_," Q. J. Micr. Sci. xlii, pp. 363-476, pls. xxxv-xli.

1901. EVANS, R., "A description of _Ephydatia blembingia_, with an account of the formation and structure of the gemmule," Q. J. Micr. Sci. xliv, pp. 71-109, pls. i-iv.

1907. WELTNER, "Spongillideustudien, V.: Zur Biologie von _Ephydatia fluviatilis_ and die Bedeutung der Amöbocyten für die Spongilliden," Arch. Naturg. Berlin, lxxiii (i), pp. 273-286.

1907. ANNANDALE, "The buds of _Spongilla proliferens_, Annand.," Rec. Ind. Mus. i, pp. 267, 268.

1907. ANNANDALE, "Embryos of _Ephydatia blembingia_, Evans," _ibid._ p. 269.

1907. ANNANDALE, "The nature of the pores in _Spongilla_," _ibid._ pp. 270-271.

(c) _Descriptions of Asiatic Species[V] and of Animals associated with them._

[Footnote V: Descriptions of Siberian sponges are not
included in these references.]

1847-1848. CARTER, "Notes on the species, structure, and animality of the Freshwater Sponges in the tanks of Bombay (Genus _Spongilla_)," Trans. Bombay Med. & Phys. Soc., 1847, and Ann. Nat. Hist. (2) i, pp. 303-311, 1848.

1849. CARTER, "A descriptive account of the Freshwater Sponges (Genus _Spongilla_) in the Island of Bombay, with observations on their structure and development," Ann. Nat. Hist. (2) iv, pp. 81-100, pls. iii-v.

1868. MARTENS, E. VON, "Ueber einige östasiatische Süsswasserthiere," Arch. Naturg. Berlin, xxxiv, pp. 1-67: IV., Ein Süsswasserschwamm aus Borneo, pp. 61-64, pl. i, fig. 1.

1881. CARTER, "On _Spongilla cinerea_," Ann. Nat. Hist. (5) vii, p. 263.

1890. WEBER, M., "Zoologische Ergebnisse einer Reise in Niederländisch Ost-Indien," i, pp. 30-47, pl. iv.

1901. EVANS, R., "A description of _Ephydatia blembingia_, with an account of the formation and structure of the gemmule," Q. J. Micr. Sci. xliv, pp. 71-109, pls. i-iv.

1901. WELTNER, "Süsswasserspongien von Celebes (Spongillidenstudien, IV.)," Arch. Naturg. Berlin, lxvii (1) (Special Number), pp. 187-204, pls. vi, vii.

1906. ANNANDALE, "A variety of _Spongilla lacustris_ from brackish water in Bengal," J. As. Soc. Bengal, (n. s.) ii, pp. 55-58.

1906. ANNANDALE, "Some animals found associated with _Spongilla carteri_ in Calcutta," _ibid._ pp. 187-196.

1907. WILLEY, "Freshwater Sponge and Hydra in Ceylon," Spolia Zeylanica, iv, pp. 184-185.

1907. ANNANDALE, "On Freshwater Sponges from Calcutta and the Himalayas," J. As. Soc. Bengal, (n. s.) iii, pp. 15-26.

1907. ANNANDALE, "Gemmules of _Trochospongilla phillottiana_, Annand.," Rec. Ind. Mus. i, p. 269.

1907. ANNANDALE, "Description of two new Freshwater Sponges from Eastern Bengal, with remarks on allied forms," _ibid._ pp. 387-392.

1908. ANNANDALE, "Preliminary notice of a collection of Sponges from W. India, with descriptions of two new species," Rec. Ind. Mus. ii, pp. 25-28.

1908. KIRKPATRICK, "Description of a new variety of _Spongilla loricata_, Weltner," _ibid._ pp. 97-99.

1908. ANNANDALE, "Preliminary notice of a collection of Sponges from Burma, with the description of a new species of _Tubella_," _ibid._ pp. 157-158.

1909. ANNANDALE, "Report on a small collection of Sponges from Travancore," Rec. Ind. Mus. iii, pp. 101-104, pl. xii.

1909. NEEDHAM, "Notes on the Neuroptera in the collection of the Indian Museum," _ibid._ pp. 206-207.

1909. ANNANDALE, "Description of a new species of _Spongilla_ from Orissa," _ibid._ p. 275.

1909. ANNANDALE, "Beiträge zur Kenntnis der Fauna von Süd-Afrika: IX. Freshwater Sponges," Zool. Jahrb. (Syst.) xxvii, pp. 559-568.

1909. ANNANDALE, "Report on a collection of Freshwater Sponges from Japan," Annot. Zool. Japon, vii, pp. 105-112, pl. ii.

1909. ANNANDALE, "Freshwater Sponges in the collection of the United States National Museum: Part I. Specimens from the Philippines and Australia," P. U.S. Mus. xxxvi, pp. 627-632.

1909. ANNANDALE, "Freshwater Sponges collected in the Philippines by the 'Albatross' Expedition," _ibid._ xxxvii, pp. 131-132.

1909. ANNANDALE, "Freshwater Sponges in the collection of the United States National Museum: Part II. Specimens from North and South America," _ibid._ pp. 401-406.

1910. ANNANDALE, "Freshwater Sponges in the collection of the United States National Museum: Part III. Description of a new species of _Spongilla_ from China," _ibid._ xxxviii, p. 183.

1910. ANNANDALE, "Description of a new species of Sponge from Cape Comorin," Rec. Ind. Mus. v, p. 31.

1910. STEPHENSON, "On some aquatic Oligochæte worms commensal in _Spongilla carteri_," _ibid._ pp. 233-240.

1910. ANNANDALE, "Note on a Freshwater Sponge and Polyzoon from Ceylon," Spolia Zeylanica, vii. p. 63, pl. i.

GLOSSARY OF TECHNICAL TERMS USED IN PART I.

_Amphioxi_ (adj. Rod-like spicules sharp at both ends.
_amphioxous_)

_Amphistrongyli_ (adj. Rod-like spicules blunt at both ends.
_amphistrongylous_)

_Basal membrane_ A horny, structureless membrane found
at the base of some sponges.

_Birotulate_ (subst. or adj.) Spicule with a transverse disk at both
ends.

_Bubble-cells_ Spherical cells of the parenchyma the
contents of which consist of a drop of
liquid covered by a thin film of
protoplasm.

_Ciliated_ (or _flagellated_) A cavity lined with collar-cells.
_chamber_

_Collar-cell_ (_choanocyte_) Cell provided at one end with a
membranous collar and a vibratile lash
or flagellum that springs from within
the collar.

_Derma_ or _ectodermal layer_ A layer of flat cells arranged like a
pavement on the surface of the sponge.

_Exhalent_ (or _efferent_) A tubular canal through which water
_canal_ passes from a ciliated chamber towards
the osculum.

_Fibres_ (skeleton) Thread-like structures that compose the
skeleton of the sponge and are formed
(in the Spongillidæ) mainly of
overlapping spicules.

_Flesh-spicules_ Microscleres (_q. v._) that lie free in
the parenchyma and the derma.

_Foramen_ An orifice of the gemmule.

_Foraminal tubule_ A horny tube that surrounds the foramina
of some gemmules.

_Gemmule_ A mass of cells packed with food-material,
surrounded by at least one horny coat,
capable of retaining vitality in
unfavourable conditions and finally of
giving origin to a new sponge.

_Green corpuscles_ Minute green bodies found inside cells
of sponges and other animals and
representing a stage in the life-history
of an alga (_Chlorella_).

_Inhalent_ (or _afferent_) A tubular canal through which water
canal passes from the exterior towards a
ciliated chamber.

_Megascleres_ The larger spicules that (in the
Spongillidæ) form the basis of the
skeleton of the sponge.

_Microscleres_ Smaller spicules that lie free in the
substance or the derma of the sponge, or
are associated with the gemmule.

_Monaxon_ (Of spicules) having a single main axis;
(of sponges) possessing skeleton spicules
of this type.

_Osculum_ An aperture through which water is
ejected from the sponge.

_Oscular collar_ A ring-shaped membrane formed by an
extension of the derma round an osculum.

_Parenchyma_ The gelatinous part of the sponge.

_Pavement layer_ Adherent gemmules arranged close together
in a single layer at the base of a sponge.

_Pneumatic coat_ A horny or chitinous layer on the surface
of the gemmule containing air-spaces.
If these spaces are of regular form and
arrangement it is said to be _cellular_;
if they are minute and irregular it is
called _granular_.

_Pore_ A minute hole through which water is
taken into the sponge.

_Pore-cell_ (_porocyte_) A cell pierced by a pore.

_Radiating fibres_ Fibres in the skeleton of a sponge that
are vertical or radiate from its centre.

_Rotula_ A transverse disk borne by a microsclere.

_Rotulate_ (subst. or adj.) Spicule bearing one or two transverse
disks.

_Spicule_ A minute mineral body of regular and
definite shape due not to the forces of
crystallization but to the activity of
the living cell or cells in which it is
formed.

_Spongin_ The horny substance found in the skeletal
framework and the coverings of gemmules
of sponges. Structures formed of
this substance are often referred to as
_chitinous_.

_Subdermal cavity_ A cavity immediately below the derma
(_q. v._).

_Transverse fibres_ Fibres in the skeleton of a sponge that
run across between the radiating fibres.

_Tubelliform_ (of spicule) Having a straight shaft with a transverse
disk at one end and a comparatively
small knob-like projection at the other.

SYSTEMATIC LIST OF THE INDIAN SPONGILLIDÆ.

[Types, schizotypes, or cotypes have been examined in the case of all species, &c., whose names are marked thus, *.]

Genus 1. SPONGILLA, Lamarck (1816).
Subgenus A. EUSPONGILLA, Vejdovsky (1883).
1. ? _S. lacustris_, auct. (perhaps in N.W. India).
1_a_. _S. lacustris_ subsp. _reticulata_*, Annandale (1907).
2. _S. proliferens_*, Annandale (1907).
3. _S. alba_*, Carter (1849).
3_a_. _S. alba_ var. _cerebellata_, Bowerbank (1863).
3_b_. _S. alba_ var. _bengalensis_*, Annandale (1906).
4. _S. cinerea_*, Carter (1849).
5. _S. travancorica_*, Annandale (1909).
6. _S. hemephydatia_*, Annandale (1909).
7. _S. crateriformis_* (Potts) (1882).
Subgenus B. EUNAPIUS, J. E. Gray (1867).
8_a_. _S. carteri_ var. _mollis_*, nov.
8_b_. _S. carteri_ var. _cava_*, nov.
8_c_. _S. carteri_ var. _lobosa_*, nov.
9_a_. _S. fragilis_ subsp. _calcuttana_*, nov.
9_b_. _S. fragilis_ var. _decipiens_, Weber (probably Malaysian,
not Indian).
10. _S. gemina_*, sp. nov.
11. _S. crassissima_*, Annandale (1907).
11_a_. _S. crassissima_ var. _crassior_*, Annandale (1907).
Subgenus C. STRATOSPONGILLA, Annandale (1909).
12. _S. indica_*, Annandale (1908).
13. _S. bombayensis_*, Carter (1882).
14. _S. ultima_*, Annandale (1910).

Genus 2. PECTISPONGILLA, Annandale (1909).
15. _P. aurea_*, Annandale (1909).
15_a_. _P. aurea_ var. _subspinosa_*, nov.

Genus 3. EPHYDATIA, Lamouroux (1816).
16. _E. meyeni_* (Carter) (1849).

Genus 4. DOSILIA, J. E. Gray (1867).
17. _D. plumosa_* (Carter) (1849).

Genus 5. TROCHOSPONGILLA, Vejdovsky (1883).
18. _T. latouchiana_*, Annandale (1907).
19. _T. phillottiana_*, Annandale (1907).
20. _T. pennsylvanica_* (Potts) (1882).

Genus 6. TUBELLA, Carter (1881).
21. _T. vesparioides_*, Annandale (1908).

Genus 7. CORVOSPONGILLA, nov.
22. _C. burmanica_* (Kirkpatrick) (1908).
23. _C. lapidosa_* (Annandale) (1908).

Order HALICHONDRINA.

Siliceous monaxon sponges in which the horny skeleton is much reduced or absent and the spicular skeleton is more or less definitely reticulate. The microscleres are usually rod-like and rarely have more than one main axis.

Family SPONGILLIDÆ.

SPONGILLADÆ, J. E. Gray, P. Zool. Soc. London, 1867, p. 550.

Freshwater Halichondrina which at certain seasons produce gemmules armed with peculiar microscleres. Two distinct kinds of microsclere are often present, that associated with the gemmule sometimes consisting of a vertical shaft at the ends of which transverse disks or rotulæ are borne. There is always at least a trace of a subdermal cavity.

Many authors divide the Spongillidæ into two subfamilies:--Spongillinæ (or Euspongillinæ), in which the gemmule-spicules have no transverse rotulæ, and Meyeninæ (or Ephydatiinæ), in which they have rotules at one or both ends. So gradual, however, is the transition that I find it difficult to decide in one instance to which of two genera, typical respectively of the two "subfamilies," a species should be assigned. Minchin in his account of the Porifera in Lankester's "Treatise on Zoology" (1900) regards the Spongillidæ merely as a subfamily of the Heterorrhaphidæ, and there certainly are few differences of a definite nature between them and the marine family (or subfamily) Remeridæ.

_Key to the Indian Genera of_ Spongillidæ.

I. Microscleres without transverse disks.
A. Microscleres of the parenchyma similar
in general structure to those or the
gemmule; the latter without comb-like
vertical rows of spines at the ends SPONGILLA, p. 67.
B. Microscleres of the gemmule with comb-like
vertical rows of spines at both ends PECTISPONGILLA, p. 106.

II. Some or all of the microscleres birotulate.
(Birotulate microscleres of one kind only.)
A. Microscleres of the gemmule birotulate, the
rotules with serrated or strongly sinuous
edges; parenchyma spicules usually absent,
never of complicated structure EPHYDATIA, p. 108.
B. Microscleres of the gemmule as in
_Ephydatia_; microscleres of the parenchyma
consisting of numerous shafts
meeting in different planes in a central
nodule DOSILIA, p. 110.
C. Microscleres as in _Ephydatia_ except
that the rotulæ of the gemmule-spicules
have smooth edges TROCHOSPONGILLA, p. 113.
D. Microscleres of the gemmule without a
trace of rotules, those of the parenchyma
birotulate CORVOSPONGILLA, nov., p. 122.

III. Microscleres of the gemmule with a well-developed
basal rotule and a vertical shaft
ending above in a mere knob. TUBELLA, p. 120.

The most distinct genus of Spongillidæ not yet found in India is _Heteromeyenia_, Potts. It is easily distinguished from all others by the fact that the birotulate spicules of the gemmule are of two quite distinct kinds, which occur together on every mature gemmule. _Heteromeyenia_ is represented by several American species, one of which has been found in Europe. _Acalle_, J. E. Gray, which is represented by a single South American species (_Spongilla recurvata_, Bowerbank), is related to _Heteromeyenia_ but has one kind of gemmule-spicule tubelliform, the other birotulate. Probably _Uraguaya_, Carter, should be regarded as a subgenus of _Trochospongilla_ with an unusually solid skeleton; it is peculiar to S. America. _Parmula_, Carter (=_Drulia_, Gray) includes South American forms allied to _Tubella_, but with the shaft of the gemmule-spicule degenerate and consisting of a mere projection in the centre of a shield-like body, which represents the lower rotule. The status of _Potamolepis_, Marshall, originally described from the Lake of Galilee, is very doubtful; possibly some or all of its species belong to the subgenus of _Spongilla_ here called _Stratospongilla_ (p. 100); but they are stated never to produce gemmules. The same is the case as regards _Pachydictyum_, Weltner, which consists of a single species from Celebes.

The sponges from Lake Baikal assigned by Weltner (Arch. Naturg. lxi (i) p. 131) to the subfamily Lubomirskinæ are of doubtful position and need not be considered here; while _Lessepsia_, Keller, from one of the salt lakes on the Suez Canal, certainly does not belong to the family, although it is assigned to it by von Lendenfeld (Mon. Horny Sponges, p. 904 (1889)) and subsequently by Minchin (Porifera, p. 152, in Lankester's Treatise on Zoology, part ii (1900)).

Genus 1. SPONGILLA, _Lamarck_ (Carter _emend._).

_Spongilla_, Lamarck, Histoire des Animaux sans Vertèbres, ii, p. 111
(1836).
_Spongilla_, Carter, Ann. Nat. Hist. (5) vii, p. 86 (1881).
_Euspongilla_, Vejdovsky, Abh. Böhm. Ges. xii, p. 15 (1883).
_Spongilla_, Potts, P. Ac. Philad. 1887, p. 182.

TYPE, _Spongilla lacustris_, auctorum.

Spongillidæ in which the gemmules have (normally) cylindrical or subcylindrical spicules that are sharp or blunt at the ends, without a distinct transverse disk or disks and without comb-like vertical rows of spines.

The skeleton is variable in structure, sometimes being almost amorphous, sometimes having well-defined radiating and transverse fibres firmly compacted with spongin. The skeleton-spicules are either sharp or blunt at the ends. Flesh-spicules are often absent; when present they are needle-like and resemble the gemmule-spicules in general structure; they have not even rudimentary rotules at their ends. The gemmules either lie free in the substance of the sponge or are attached to its support; sometimes they adhere together in free or attached groups.

_Spongilla_ is undoubtedly the most primitive genus of the Spongillidæ, its spicules showing less sign of specialization than those of any other genus included in the family. As a fossil it goes back at any rate to the Upper Jurassic (p. 52).

GEOGRAPHICAL DISTRIBUTION.--Cosmopolitan. In most countries the majority of the freshwater sponges belong to this genus, but in Japan _Ephydatia_ seems to predominate.

_Key to the Indian Species of_ Spongilla.

I. Gemmule provided with a thick, apparently
granular pneumatic coat in
which the gemmule-spicules are arranged
tangentially or vertically. (Subgenus
_Euspongilla_, p. 69.)
A. No foraminal tubule.
_a._ Sponge bright green, soft and
compressiblewhen fresh, very fragile
dry _lacustris_, p. 69.
_a'._ Sponge white or grey, hard both
fresh and dry _alba_, p. 76.
B. A foraminal tubule present.
_b._ Skeleton-spicules smooth.
beta. Gemmules free; gemmule-spicules
arranged tangentially and
horizontally _proliferens_, p. 72.
beta'. Gemmules free; gemmule-spicules
arranged vertically or nearly
so in a single series _hemephydatia_, p. 82.
beta''. Gemmules firmly fixed
to the support of the sponge;
gemmule-spicules almost vertical,
irregularly arranged, as a rule in
more than one series _travancorica_, p. 81.
_b'._ Skeleton-spicules spiny or
irregular in outline.
beta'''. Gemmule-spicules tangential
and horizontal, without
rudimentary rotules _cinerea_, p. 79.
beta''''. Gemmule-spicules vertical or
nearly so, often with
rudimentary rotules at the tips _crateriformis_, p. 83.

II. Gemmules surrounded in several layers
by distinct polygonal air-spaces with
chitinous walls. (Subgenus _Eunapius_,
p. 86.)
A. Gemmules single. Skeleton- and
gemmule-spicules smooth, pointed,
not very stout _carteri_, p. 87.
B. Gemmules bound together in pairs.
Skeleton friable; skeleton-spicules
slender _gemina_, nov., p. 97.
C. Gemmules bound together in free
groups of more than two or forming
a "pavement-layer" at the base of
the sponge.
_c._ Skeleton friable;
skeleton-spicules slender _fragilis_, p. 95.
_c'._ Skeleton very hard and
resistant; skeleton-spicules stout _crassissima_, p. 98.

III. Gemmules without or with irregular
pneumatic coat, covered by a chitinous
membrane or membranes in which the
gemmule-spicules lie parallel to the
surface. (Subgenus _Stratospongilla_,
p. 100.)

A. Skeleton spicules spiny or irregular in
outline.

_a._ Skeleton-spicules blunt; gemmules
covered by a single chitinous
membrane _indica_, p. 100.

_a'._ Skeleton-spicules sharp; gemmules
covered by two chitinous membranes _bombayensis_, p. 102.

B. Skeleton-spicules smooth.
Skeleton-spicules sharp; gemmule
spicules very irregular in form _ultima_, p. 104.

Subgenus A. EUSPONGILLA, _Vejdovsky_.

_Euspongilla_, Vejdovsky, Abh. Böhm. Ges. xii, p. 15 (1883).
_Euspongilla_, _id._, in Potts's "Fresh-Water Sponges," P. Ac. Philad.
1887, p. 172.
_Euspongilla_, Weltner, in Zacharias's Tier- und Pflanzenwelt des
Süsswassers, i, p. 210 (1891).

TYPE, _Spongilla lacustris_, auctorum.

Spongillæ in which the gemmules are covered with a thick, apparently granular pneumatic coat. A delicate membrane often occurs outside this coat, but it is never thick or horny. The gemmules usually lie free in the sponge but sometimes adhere to its support; rarely they are fastened together in groups (_e. g._ in _S. aspinosa_, Potts). The skeleton-spicules are never very stout and the skeleton is always delicate.

The species in this subgenus are closely allied and must be distinguished rather by the sum of their peculiarities than by any one character. They occur in all countries in which Spongillidæ are found. Seven Indian species may be recognized.

1. Spongilla lacustris, _auctorum_.

_Spongilla lacustris_, Bowerbank, P. Zool. Soc. London, 1863, p. 441,
pl. xxxviii, fig. 14.
_Spongilla lacustris_, Carter, Ann. Nat. Hist. (5) vii, p. 87 (1881).
_Euspongilla lacustris_, Vejdovsky, in Potts's "Fresh-Water Sponges,"
P. Ac. Philad. 1887, p. 172.
_Spongilla lacustris_, Potts, _ibid._, p. 186, pl. v, fig. 1, pl. vii,
figs. 1-6.
_Euspongilla lacustris_, Weltner, in Zacharias's Tier- und Pflanzenwelt
des Süsswassers, i, p. 211, figs. 36-38 (1891).
_Spongilla lacustris_, _id._, Arch. Naturg. lxi (i), pp. 118, 133-135
(1895).
_Spongilla lacustris_, Annandale, J. Linn. Soc., Zool., xxx, p. 245
(1908).

[I have not attempted to give a detailed synonymy of this
common species. There is no means of telling whether many of
the earlier names given to forms or allies of _S. lacustris_
are actual synonyms, and it would serve no useful purpose,
so far as the fauna of India is concerned, to complicate
matters by referring to obscure descriptions or possible
descriptions of a species only represented in India, so far
as we know, by a specialized local race, to which separate
references are given.]

_Sponge_ soft and easily compressed, very brittle when dry, usually consisting of a flat or rounded basal portion of no great depth and of long free cylindrical branches, which droop when removed from the water; branches occasionally absent. Colour bright green when the sponge is growing in a strong light, dirty flesh-colour when it is growing in the shade. (Even in the latter case traces of the "green corpuscles" can be detected in the cells of the parenchyma.) Oscula star-shaped, of moderate size, as a rule rendered conspicuous by the furrows that radiate from them over the outer surface of the parenchyma below the external membrane; oscular collars well developed.

_Skeleton_ reticulate, loose, with definite radiating and transverse fibres held together by a small quantity of spongin; the fibres slender but not extremely so.

_Spicules._ Skeleton-spicules smooth, sharply pointed, long, slender. Flesh-spicules slender, covered with small spines, sharply pointed, nearly straight. Gemmule-spicules resembling the flesh-spicules but shorter and as a rule more strongly curved, sometimes bent so as to form semicircular figures, usually pointed somewhat abruptly; their spines relatively longer than those of the flesh-spicules, often curved backwards, especially near the ends of the spicules, at which points they are often longer than elsewhere.

_Gemmules_ usually numerous in autumn, lying free in the sponge, spherical, variable in size but usually rather large, as a rule covered with a thick granular coat in which the spicules are arranged tangentially; a horizontal layer of spicules often present in the external membrane; the granular coat and its spicules occasionally deficient. No foraminal tubule; its place sometimes taken by an open, bowl-shaped chitinous structure the base of which is in continuity with the inner chitinous coat of the gemmule.

_S. lacustris_ is an extremely variable species, varying in the size, proportions and shape of its spicules, in its external form and in the size and structure of the gemmule. A considerable number of varieties have been described from different parts of Europe and N. America, but some of these may represent distinct but closely-allied species; descriptions of most of them will be found in Potts's "Fresh-Water Sponges." The embryology and the earlier stages of the development from the egg have been described in great detail by Evans (Quart. J. Micr. Sci. (n. s.) xlii, p. 363 (1899)), while the anatomy and physiology are discussed by most authors who have written on these features in the Spongillidæ.

TYPE.--It is impossible to say who was the first authority to use the name _Spongilla lacustris_ in the sense in which it is used by recent authors. No type can therefore be recognized.

GEOGRAPHICAL DISTRIBUTION.--_S. lacustris_ occurs all over Europe and N. America and is probably the commonest species in most parts of both continents. It has also been found in Northern Asia and may occur in the Himalayan lakes and in the north-west of India.

1 _a._ Subspecies reticulata*, _Annandale_.

_Spongilla reticulata_, Annandale, Rec. Ind. Mus. i, p. 387,
pl. xiv, fig. 1 (1907).

_Spongilla lacustris_ subspecies _reticulata_, _id._, P.
U.S. Mus. xxxvii, p. 401 (1909).

This race differs from the typical _S. lacustris_ in the following particulars:--

(1) The branches are always compressed and anastomose
freely when well developed (fig. 5, p. 37);

(2) the skeleton-fibres are finer;

(3) the skeleton-spicules are longer;

(4) the gemmule-spicules are longer and more slender and are
never strongly bent.

A=gemmule-spicules of _Spongilla lacustris_ subsp. _reticulata_ (from type); B=gemmule-spicules of _S. alba_ from Calcutta: both highly magnified.]

As regards the form of the skeleton- and gemmule-spicules and also that of the branches the subspecies _reticulata_ resembles _S. alba_ rather than _S. lacustris_, but owing to the fact that it agrees with _S. lacustris_ in its profuse production of branches, in possessing green corpuscles and in its fragility, I think it should be associated with that species.

The branches are sometimes broad (fig. 5, p. 37), sometimes very slender. In the latter condition they resemble blades of grass growing in the water.

TYPE in the Indian Museum; a co-type in the British Museum.

GEOGRAPHICAL DISTRIBUTION.--All over Eastern India and Burma; also in the Bombay Presidency. _Localities:_--BENGAL, Port Canning, Ganges delta; Rajshahi (Rampur Bhulia) on the Ganges, 150 miles N. of Calcutta (_Annandale_); Puri district, Orissa (_Annandale_); R. Jharai, Siripur, Saran district, Tirhut (_M. Mackenzie_): MADRAS PRESIDENCY, Madras (town) (_J. R. Henderson_): BOMBAY PRESIDENCY, Igatpuri, W. Ghats (_Annandale_).

BIOLOGY.--This subspecies is usually found in small masses of water, especially in pools of rain-water, but Mr. Mackenzie found it growing luxuriantly in the Jharai at a time of flood in September. It is very abundant in small pools among the sand-dunes that skirt the greater part of the east coast of India. Here it grows with great rapidity during the "rains," and often becomes desiccated even more rapidly as soon as the rain ceases. As early in the autumn as October I have seen masses of the sponge attached, perfectly dry, to grass growing in the sand near the Sur Lake in Orissa. They were, of course, dead but preserved a life-like appearance. Some of them measured about six inches in diameter. At Port Canning the sponge grows during the rains on the brickwork of bridges over ditches of brackish water that dry up at the beginning of winter, while at Rajshahi and at Igatpuri I found it at the edges of small ponds, at the latter place in November, at the former in February. Specimens taken at Madras by Dr. Henderson during the rains in small ponds in the sand contained no gemmules, but these structures are very numerous in sponges examined in autumn or winter.

Numerous larvæ of _Sisyra indica_ (p. 92) were found in this sponge at Rajshahi. Unlike those obtained from _S. alba_, they had a green colour owing to the green matter sucked from the sponge in their stomachs. The _coralloides_ phase of _Plumatella fruticosa_ (p. 219) was also found in _S. lacustris_ subsp. _reticulata_ at Rajshahi.

So far as my experience goes, this subspecies has always a bright green colour due to the presence of "green corpuscles," even when it is growing in a pond heavily shaded by trees or under the arch of a small bridge. Probably the more intense light of India enables the corpuscles to flourish in situations in which in Europe they would lose their chlorophyll.

2. Spongilla proliferens*, _Annandale_.

_Spongilla cinerea_, Weber (_nec_ Carter), Zool. Ergeb.
Niederl. Ost-Ind. vol. i, pp. 35, 46 (1890).

_Spongilla proliferens_, Annandale, J. Asiat. Soc. Bengal,
1907, p. 15, fig. 1.

_Spongilla proliferens_, _id._, Rec. Ind. Mus. i, pp. 267,
271 (1907).

_Sponge_ forming soft, shallow cushions rarely more than 10 cm. in diameter on the leaves of water-plants, or small irregular masses on their roots and stems. Colour bright green. Oscula moderate, flat, surrounded by deep, cone-shaped collars; radiating furrows and canals in the parenchyma surrounding them often deep. External pores contained normally in single cells. The surface frequently covered by small rounded buds; true branches if present more or less flattened or conical, always short, as a rule absent.

_Skeleton_ loose, feebly reticulate at the base of the sponge; transverse fibres slender in the upper part of the sponge, often scarcely recognizable at its base. Very little spongin present.

_Spicules._ Skeleton-spicules long, smooth, sharply pointed; the length on an average at least 20 times the greatest breadth, often more. Flesh-spicules slender, gradually pointed, nearly straight, covered with minute straight or nearly straight spines. Gemmule-spicules very similar, but usually a little stouter and often blunt at the ends; their spines rather longer than those on the flesh-spicules, usually more numerous near the ends than in the middle of the spicule, slightly retroverted, those at the extreme tips often so arranged as to suggest a rudimentary rotule.

_Gemmules_ usually numerous, lying free near the base of the sponge, very variable in size, spherical, surrounded by a thick granular layer in which the spicules, which are always very numerous, are arranged tangentially, their position being more near the vertical than the horizontal; a few horizontal spicules usually present on the external surface of the gemmule, which frequently has a ragged appearance owing to some of the tangential spicules protruding further than others. Foraminal tubule stout, cylindrical, usually somewhat contorted; its orifice irregular in outline. Sometimes more than one foramen present.

_S. proliferens_ can be distinguished from all forms of _S. lacustris_ and _S. alba_ by the fact that its gemmules possess a foraminal tubule; from _S. cinerea_ it can be distinguished by its colour and its smooth skeleton-spicules, and from _S. travancorica_ by its free gemmules. I have been enabled by the kindness of Prof. Max Weber to examine specimens from Celebes and Java identified by him as _S. cinerea_, Carter, and have no doubt that they belong to my species.

TYPE in the Indian Museum; a co-type in the British Museum.

GEOGRAPHICAL DISTRIBUTION.--All over Eastern India and Burma; also in Cochin on the west coast; Ceylon; W. China; Java, Flores and Celebes. _Localities_:--BENGAL, Calcutta and neighbourhood (_Annandale_); Berhampore, Murshidabad district (_R. E. Lloyd_): ASSAM, Mangal-dai near the Bhutan frontier (_S. W. Kemp_): MADRAS PRESIDENCY, Madras (town) and neighbourhood (_J. R. Henderson_); Rambha, Ganjam district (_Annandale_); Bangalore, Mysore (alt. _ca._ 3000 ft.) (_Annandale_); Ernakulam and Trichur, Cochin (_G. Mathai_): BURMA, Rangoon (_Annandale_, _J. Coggin Brown_); Prome, Upper Burma (_J. Coggin Brown_); Kawkareik, Amherst district, Tenasserim (_Annandale_): CEYLON, between Maradankawela and Galapita-Gala, North Central Province (_Willey_). Mr. J. Coggin Brown has recently brought back specimens from Yunnan.

BIOLOGY.--_S. proliferens_ is usually found in ponds which never dry up; Prof. Max Weber found it in small streams in Malaysia. It is common in India on the leaves of _Vallisneria_ and _Limnanthemum_, on the roots of _Pistia stratiotes_ and on the stems of rushes and grass. So far as I have been able to discover, the life of the individual sponge is short, only lasting a few weeks.

Sexual reproduction occurs seldom or never, but reproduction by means of buds and gemmules continues throughout the year. The former is a rare method of reproduction in most Spongillidæ but in this species occurs normally and constantly, the buds being often very numerous on the external surface. They arise a short distance below the surface as thickenings in the strands of cells that accompany the radiating fibres of the skeleton. As they grow they push their way up the fibres, forcing the external membrane outwards. The membrane contracts gradually round their bases, cuts off communication between them and the parent sponge and finally sets them adrift. No hole remains when this takes place, for the membrane closes up both round the base of the bud and over the aperture whence it has emerged.

The newly liberated bud already possesses numerous minute pores, but as yet no osculum; its shape exhibits considerable variation, but the end that was farthest from the parent-sponge before liberation is always more or less rounded, while the other end is flat. The size also varies considerably. Some of the buds float, others sink. Those that float do so either owing to their shape, which depends on the degree of development they have reached before liberation, or to the fact that a bubble of gas is produced in their interior. The latter phenomenon only occurs when the sun is shining on the sponge at the moment they are set free, and is due to the action of the chlorophyll of the green bodies so abundant in certain of the parenchyma cells of this species. If the liberation of the bud is delayed rather longer than usual, numbers of flesh-spicules are produced towards the ends of the primary skeleton-fibres and spread out in one plane so as to have a fan-like outline; in such buds the form is more flattened and the distal end less rounded than in others, and the superficial area is relatively great, so that they float more readily. Those buds that sink usually fall in such a way that their proximal, flattened end comes in contact with the bottom or some suspended object, to which it adheres. Sometimes, however, owing to irregularity of outline in the distal end, the proximal end is uppermost. In this case it is the distal end that adheres. Whichever end is uppermost, it is in the uppermost end, or as it may now be called, the upper surface, that the osculum is formed. Water is drawn into the young sponge through the pores and, finding no outlet, accumulates under the external membrane, the subdermal cavity being at this stage even larger than it is in the adult sponge. Immediately after adhesion the young sponge flattens itself out. This process apparently presses together the water in the subdermal cavity and causes a large part of it to accumulate at one point, which is usually situated near the centre of the upper surface. A transparent conical projection formed of the external membrane arises at this point, and at the tip of the cone a white spot appears. What is the exact cause of this spot I have not yet been able to ascertain, but it marks the point at which the imprisoned water breaks through the expanded membrane, thus forming the first osculum. Before the aperture is formed, it is already possible to distinguish on the surface of the parenchyma numerous channels radiating from the point at which the osculum will be formed to the periphery of the young sponge. These channels as a rule persist in the adult organism and result from the fact that the inhalent apertures are situated at the periphery, being absent from both the proximal and the distal ends of the bud. In the case of floating buds the course of development is the same, except that the osculum, as in the case of development from the gemmule in other species (see Zykoff, Biol. Centrbl. xii, p. 713, 1892), is usually formed before adhesion takes place.

The sponge of _S. proliferens_ is usually too small to afford shelter to other animals, and I have not found in it any of those commonly associated with _S. carteri_ and _S. alba_.