Chapter V: Microscopic Fauna

BY THOMAS BOLTON, F.R.M.S.

The writer in drawing up the following summary of the local Microscopic Fauna, knowing how limited a space is allowed, has in several of the families given only the more rare and remarkable species which have come under his own observation. The organisms included in this division are abundant all round Birmingham; in the canals, reservoirs, and rivers, in the swags and catchpits, amongst the spoil heaps of the “Black Country,” and in the numerous clay-pits on the farm lands.

INSECTA.

It is desirable to call attention to the identification of the larvæ of the Trichopterous insects _Agraylea multipunctata_ and _Oxyethira costalis_, by Messrs. Kenneth J. Morton and Robert McLachlan. The perfect insects were bred from larvæ collected in this district, as referred to in the “Entomologists’ Monthly Magazine,” May and June, 1886. So many problems in the life history of insects, having aquatic larvæ, remain unsolved, that it is desirable that microscopists should pay more attention to this subject.

ARACHNIDA.

The curious Diving-bell Spider, _Argyroneta aquatica_, is found in the pools at Sutton Park; and a great variety of species of the Water-Mites is generally distributed. Mr W. Saville Kent reports that several specimens received from this district are new to science.

Tardigrada, viz., _Macrobiotus Hufelandii_, and other species, may be found almost everywhere, if carefully looked for amongst damp moss and decaying algæ.

CRUSTACEA.

In this class should be mentioned the freshwater Crayfish, _Astacus fluviatilis_, not of course a microscopic organism; but if it were omitted here it would not appear in any of the other reports. This species is fairly distributed in most of the smaller brooks, in the canals, and larger reservoirs, but is not so abundant or so large as it is on the lime formations round Oxford. Two other large microscopic species of this class, the freshwater Shrimp, _Gammarus pulex_, and the water Wood-louse, _Asellus vulgaris_, are always present, the former busy in its office of scavenger in the sandy bottoms of the brooks and ditches, and the latter climbing about, like a monkey, amongst the water weeds, investigating the mass of living and decaying organisms with which the weeds are clothed.

ENTOMOSTRACA.

The members of this sub-class are also to be found everywhere, but it is desirable to call special attention to the discovery for the first time in Great Britain of the wonderfully transparent _Leptodora hyalina_, at a visit of the Birmingham Natural History and Microscopical Society in 1879, to the Olton Reservoir, near Solihull. It has since been found in many localities, and is very abundant in the summer and autumn in the Warwick Canal and several reservoirs. _Hyalodaphnia Kahlbergensis_ is very generally found with it. _Argulus coregoni_ is found in the Birmingham and Warwick Canal. It had only been discovered in Great Britain previously in the tanks of the Royal Aquarium at Westminster, which, of course, are not used for British fish exclusively. The Fairy-shrimp, _Chirocephalus diaphanus_, is found in only one locality in the district, near Knowle. A few specimens of the very rare _Lynceus acanthocercoides_ were found near Bewdley, and amongst other local finds may be mentioned _Moina rectirostris_, _Macrothrix roseus_, and _Ilyocryptus sordidus_.

POLYZOA.

These are generally distributed; _Alcyonella fungosa_, _Plumatella repens_, _Fredericella sultana_, and _Paludicella Ehrenbergii_ cover the root-fibres under the banks of the River Avon, at Evesham. _Lophopus crystallinus_ is occasionally found in the brooks to the south west of Birmingham. _Cristatella mucedo_ is often very abundant in the larger reservoirs at Sutton Park, Barnt Green, Olton, &c. Fredericella and Paludicella, have several times been seen in the town water supplied by the Corporation.

ROTIFERA.

The district appears to be very rich in these organisms, and a good number of new species from this locality are enumerated in the admirable Monograph on this family now being published by Dr. C. T. Hudson and Mr. P. H. Gosse. In the five parts already published (July 12th, 1886), they record one hundred and ninety-two species, of which ninety-eight have been found in this district, twenty-two being new species. Of the fifteen Flosculariæ eight species have been found here, viz., _Flosculariæ regalis_ (new), _F. coronetta_, _F. ornata_, _F. cornuta_, _F. campanulata_, _F. ambigua_, _F. calva_, and _F. mutabilis_ (new). _Stephanoceros Eichhornii_ may sometimes be seen quite clothing the water weeds in the canals and pools. The always attractive building Wheel-animalcule, _Melicerta ringens_, is occasionally present in abundance in the canals, rivers, and pools all over the district. The writer has taken _Melicerta conifera_ several times. _Melicerta tubicolaria_ was found by Dr. Hudson in Sutton Park, and has since been found in other localities in this district. _Limnias ceratophylli_ is very generally abundant. _Limnias annulatus_ has been found in two places. _Œcistes cystallinus_ is common, and _Œ. intermedius_ not uncommon. Although beyond the radius, it may be interesting to note that _Melicerta Janus_, new to England, was taken in one of the Shropshire meres, by the writer on the 23rd of June, 1886. It had only been found in Scotland before, by Mr. Hood, in 1880. The new rotifer, _Œcistes umbella_, was found by Mr. A. W. Wills, together with the rare _Œ. pilula_ in a pool at Sutton Park. The charming clustered rotifer, _Lacinularia socialis_, only appears in the hot summer months, but was surprisingly abundant last year in the River Avon at Warwick, literally clothing the weeds with life. This rotifer was in fair abundance a few years back in the Barnt Green Reservoir, and last year in the neighbouring canal. The still more charming free-swimming clustered rotifer, _Conochilus volvox_, is more generally present, but is not always easy to detect, on account of its transparency and continuous quick movements. The writer has taken this rotifer in the pools at Sutton Park with a muslin net in such abundance as to form quite a jelly at the bottom of the net. He also found a new species, _Conochilus dossuarius_, in 1884. Of the Philodinidæ, the following have been found--_Philodina roseola_, _P. citrina_, _P. megalotrocha_, _P. aculeata_; _Rotifer vulgaris_, _R. tardus_, _R. macroceros_, _R. macrurus_; _Actinurus Neptunius_, _Callidina elegans_, and _Adineta vaga_. The rare and pretty little _Microdon clavus_ may be found swimming about in Coleshill pool. Asplanchna, Synchæta, Polyarthra, and Triarthra, may be netted in enormous numbers in the summer months, especially in all the canals and larger pools, and they occasionally abound in the smaller pools and even in ditches, together with a great variety of the creeping ones, such as Philodina, Rotifer, Notommata, Brachionus, Anuræa, &c. The wonderful variety of these living together in a small ditch in Sutton Park is reported upon in a short paper read by the writer before the Birmingham Natural History and Microscopical Society in February last, and published in the “Midland Naturalist,” July, 1886. _Hydatina senta_ and _Rhinops vitrea_ may be looked for amongst the _Euglena viridis_ often seen luxuriating in farm yard drainage. The abnormal species, _Pedalion mira_, was found at Knowle in 1884, in fair abundance. The spiny _Anuræa longispina_ was found at Olton Reservoir very soon after it was first discovered in America, and it soon afterwards abounded in the town water, and may be found in most large reservoirs.

ANNELIDA, ETC.

Some interesting examples of the Oligochæta have been found in this locality, most of which have been identified by Professor E. Ray Lankester or Mr. E. C. Bousfield, and of these the following are noteworthy--_Chætogaster limnæi_, and _C. diaphanus_, _Nais hamata_, _N. lurida_, _N. appendiculata_, and _N. barbata_; _Stylaria parasitica_, _Dero digitata_, _D. obtusa_, _D. Perrieri_, _D. limosa_, and _D. crassa_; _Salvina serpentina_, and _Ælosoma quaternarium_. The Cercaria (the larva of a fluke) which infests the common Water Snail, _Limnæa stagnatis_, is occasionally found; also _Mesostomum rostratum_, _Derostomum vorax_, _Planaria lactea_, and _Piscicola geometrica_.

HYDROZOA.

Both _Hydra vulgaris_ and _H. viridis_ are of course found everywhere. _Cordylophora lacustris_, which is usually more abundant in brackish water, was found last year in the canal at Hamstead, near Handsworth. The writer has found it in the Stourbridge canal, and in the River Stour. Some years back the writer heard of a canal boat being docked at Dudley Port which was found to be clothed with this Hydrozoon as with velvet.

SPONGIDA.

The freshwater sponges, _Spongilla fluviatilis_ and _S. lacustris_, are abundant, but no one has taken up the subject in this district, to work out the different species into which this genus is now divided.

INFUSORIA.

When Mr. W. Saville Kent was preparing his manual on this subject, he was supplied with a great variety of specimens from this district, many of which proved to be new ones. The following are worthy of mention: _Anthophysa vegetans_, _Rhipidodendron Huxleyi_, _Spongomonas intestinalis_; various _Codosigæ_ and other Choano-flagellate monads, including _Salpingœca Boltoni_, Kent, (new); _Euglena acus_; _Dinobryon sertularia_; _Synura uvella_; _Uroglena volvox_ (very general); _Distigma proteus_; _Hemidinium nasutum_; _Peridinium tabulatum_; _Ceratium longicorne_; _Nassula ornata_; _Trachelius ovum_; _Spirostomum teres_, and _S. ambiguum_; _Stentor polymorphus_, _S. Barretti_, _S. cœruleus_, and _S. niger_; _Folliculina Boltoni_, Kent (new.) The writer has found several free swimming Tintinnus, not corresponding with any that Mr. W. Saville Kent enumerates; _Didinium nasutum_; _Trichodina pediculus_; _Scyphidium Fromentellii_; _Spirochona gemmipara_; _Vorticella chlorostigma_, and _V. monilata_; _Carchesium polypinum_, and _C. epistylidis_; _Zoothamnium arbuscula_; _Vaginicola tincta_; _Thuricola folliculata_; _Cothurnia imberbis_; _Ophrydium versatile_, _O. Eichhornii_, and _O. sessile_; _Stichotricha remex_; _Atineta lemnarum_, _A. grandis_, and _A. mystacina_; _Dendrosoma radians_.

RHIZOPODA.

The following have been found: _Amœba proteus_, _A. verrucosa_, _A. radiosa_, and _A. villosa_; _Ouramœba vorax_; _Lithamœba vorax_, Lankester (new); _Difflugia pyriformis_, _D. spiralis_, and _D. corona_; _Cyphoderia umbella_; _Arcella vulgaris_; _Actinophrys sol_; _Raphidiophrys pallida_, and _R. elegans_; _Actinosphærium Eichhornii_; _Acanthocystis chætophora_; _Archerina Boltoni_, Lankester (new); _Clathrulina elegans_, and _Biomyxa vagans_.