Chapter X (2)

Streptaxis 9
Ennea 8
Helicarion 15
Girasia 14
Austenia 11
Ibycus 1
Africarion 2
Durgella 4
Ariophanta 15
Xesta 8
Macrochlamys 78
Microcystis 7
Sitala 20
Kaliella 35
Hemiplecta 15
Sesara 3
Trochomorpha 5
Trochomorphoides 1
Parmacella (?) 1
Tebennophorus 1
Anadenus 4
Plectopylis 11
Plectotropis 3
Trachia 12
Thysanota 1
Camaena 1
Amphidromus 2
Boysia 1
Petraeus 14
Cerastus 6
Rachis 5
Cylindrus 1
Pupa 15
Hapalus 4
Clausilia 10
Subulina 2
Opeas 6
Glessula 49
Geostilbia 3
Succinea 11
Lithotis 2
Vaginula 1
Camptonyx 1
Coelostele 1
Carychium 3
Ancylus 1
Limnaea 7
Camptoceras 3
Planorbis 10
Ampullarina 1
Melania 17
Mainwaringia 1
Paludomus 10
Stomatodon 1
Larina 1
Cremnoconchus 3
Fairbankia 2
Tricula 1
Bithynia 9
Fossarulus 1
Stenothyra 3
Vivipara 4
Valvata 1
Ampullaria 4
Assiminea 9
Acmella 2
Pomatias 4
Diplommatina 63
Pupina 1
Streptaulus 1
Coptochilus 3
Alycaeus 49
Lagochilus 1
Cyclophorus 12
Scalaina 1
Micraulax 2
Jerdonia 10
Spiraculum 4
Otopoma 1
Cyclotopsis 2
Georissa 1
Modiola 1
Scaphula 1
Unio 40
Solenaia 1
Cyrena 13
Sphaerium 1
Pisidium 5
Velorita 2
Tanysiphon 1
Novaculina 1
Nausitora 1

_The Cingalese district_, which almost approaches the character of a distinct province, presents several remarkable points of dissimilarity from the rest of India. It consists of the island of Ceylon, and of a portion of S. India whose exact limits have yet to be defined. It appears, however, that the Western or Malabar coast, with the hills parallel to it, is more akin to Ceylon than the Eastern or Coromandel coast. The Travancore, Malabar, and S. Canara districts, with the Palnai, Anamalai, and Nilghiri Hills, are markedly Cingalese, while there seems to be no distinct evidence of similar relationship on the part of the Madras or even the Cuddalore district.

Among the principal features of the Cingalese district is the occurrence of three peculiar genera of _Helix_, one (_Acavus_) large and finely coloured, another (_Corilla_) smaller, with a singularly toothed aperture. While the _Corilla_ group shows relations with _Plectopylis_ and other Burmese and Siamese sub-genera _Acavus_ (Fig. 204) is totally distinct from any other Indian form, and shows signs of close relationship, in the great size of the embryonic shell, to the Helices of Madagascar (p. 335). In Ceylon the group is entirely isolated, and its occurrence, besides decisively separating that island from India, Burmah, and Siam, forms a most interesting problem in the history of distribution. _Eurystoma_, with a single species (_E. vittata_ Müll.), is also peculiar.

As usual when _Helix_ gains ascendancy, the Naninidae retrogress. _Durgella_, _Austenia_, and _Girasia_ are absent altogether, while _Macrochlamys_, _Sitala_, _Kaliella_, etc., are present in greatly diminished numbers. The sub-genus _Beddomea_ is peculiar, a form directly related to _Amphidromus_ (Siam and Malacca). The fresh-water operculate _Philopotamis_ is peculiar, but for one species found in Sumatra; while _Tanalia_ is quite peculiar. But the forms which, next to the _Helices_, most emphasise the separation of the Cingalese district are the land operculates. There are eleven genera or sub-genera of land operculates which do not occur in the rest of India proper. Two (_Aulopoma_ and _Cataulus_) are quite peculiar, while the other nine are represented in Burmah, Siam, and the Malay islands, but not in India. On the other hand, _Diplommatina_ and _Alycaeus_, so profusely abundant in India, have not yet been discovered in Ceylon. Among the slugs, _Tennentia_ is a peculiar genus, whose nearest relation occurs in the Seychelles.

_Genera and Subgenera occurring in the Cingalese District, but not in N. and Central India_

Streptaxis
Tennentia
Acavus
Eurystoma
Corilla
Beddomea
Philopotamis
Tanalia
Theobaldius
Leptopomoides
Craspedotropis
Pterocyclus
Aulopoma
Ditropis
Cyathopoma
Mychopoma
Cataulus
Nicida
Opisthostoma

The district consisting of _Upper Burmah_, _Pegu_, _Tenasserim_, and _Aracan_, while essentially a part of the Indian province, contains several Siamese genera which are not found in India proper, as well as several which are at present peculiar. Amongst the former category are, of Helicidae, a single representative each of the genera _Camaena_ (Siamese and Chinese) and _Aegista_ (Chinese). Influence of the same kind is seen in the increased numbers of _Plectopylis_ (14 sp.) and _Plectotropis_ (5 sp.), of _Clausilia_ (10 sp.) and _Amphidromus_ (5 sp.), and of the large tubed operculates (11 sp. in all). _Sesara_ and _Sophina_ among the Naninidae are strange to India, while _Hyalimax_ is common only to the Andamans, Nicobars, and Mascarene Is. _Hypselostoma_ (Fig. 202, A) is a most remarkable genus of the Pupidae, reminding one of _Anostoma_ of the New World. It is peculiar to the peninsula, but for one species in the Philippines. Among the Pupinidae, we have the peculiar _Raphaulus_ and _Hybocystis_ (Fig. 205), a very remarkable form, of which another species occurs at Perak. Two _Helicina_ mark the most westward extension of the genus on the mainland. In the extreme north of Upper Burmah, Indian and Chinese forms intermingle.

The Burmese district, together with the Indian and Siamese provinces, is pre-eminently the home of a group of Mollusca, originally of marine origin, which have permanently habituated themselves to a brackish or fresh-water existence. They belong to widely different families, and even Orders. Besides _Cremnoconchus_ mentioned above, we have, among the bivalves, _Novaculina_, a _Solen_ living in fresh water in the Ganges, Irawadi, and Tenasserim estuaries; _Scaphula_, an _Arca_, one species of which occurs in the Ganges hundreds of miles above the tide-way (see Fig. 9, p. 14); and _Martesia_, a _Pholas_ from the Irawadi Delta. _Clea_ (which also occurs in Java and Sumatra) is probably an estuarine _Cominella_; a _Tectura_ has earned the name _fluminalis_ from its exclusive residence in the Irawadi R.; _Iravadia_ is probably a _Rissoina_ of similar habits, occurring from Ceylon round to Hong-Kong; _Brotia_ is a _Cerithium_ from an affluent of the River Salwin, and _Canidia_ is a _Nassa_, occurring in the embouchures of rivers from India to Borneo. Nowhere else in the world is there such a collection--not exhausted by this list--of marine forms caught in process of habituation to a fresh-water or even a land existence.

The _Andaman_ and _Nicobar_ Islands possess no peculiar features in their land Mollusca. They are closely related to the adjacent coasts of Lower Burmah. _Amphidromus_ (2 sp.) occurs in the Andamans alone, and _Clausilia_ (2 sp.) in the Nicobars alone, while _Hyalimax_ occurs in both groups. A remarkable _Helix_ (_codonodes_ Fér.) from the Nicobars appears to find its nearest relations in the isolated group from Busuanga and Mindoro (p. 315). Land operculates are abundant, in the Nicobars actually outnumbering the pulmonates (28 to 22). _Helicina_ and _Omphalotropis_, genera characteristic of small islands, are found on both groups.

(_b_) The _Siamese Province_ includes the area occupied by the districts known as Siam, Laos, Cambodia, Cochin China, Annam, and Tonquin. Along the whole of its northern frontier, the zoological is no more than a political boundary, while on the east the mountain ranges which part Siam from Pegu and Tenasserim are not of sufficient height to offer any effective barrier to distribution. The province is accordingly qualified to a considerable extent by Indian and Chinese elements.

_Streptaxis_ is, but for three _Ennea_, the sole representative of the carnivorous genera, and attains its maximum in the Old World. Partly owing to Chinese influence, the Helicidae, with 11 genera and 46 species, begin to regain their position as compared with the Naninidae (12 genera, 54 species). Of the Helicidae, _Acusta_ and _Hadra_ appear now for the first time, and, with _Plectotropis_, _Stegodera_, and _Clausilia_, form a marked Chinese element. _Amphidromus_, with 33 species, is the most characteristic land pulmonate. Several genera, whose nucleus of distribution lies among the islands farther east, appear to have penetrated as far as these coasts. Such are _Chloritis_, _Camaena_, and _Obbina_ among the Helicidae, _Trochomorpha_, and, of the operculates, _Helicina_.

Land operculates are very richly developed. In all, there are 17 genera and 104 species known. The tubed operculates attain their maximum, and _Cyclophorus_ is even more abundant than in India. Fresh-water bivalves abound. _Dipsas_ and _Pseudodon_ are common to China, and _Unio_ and _Anodonta_ are profusely represented. A curious resemblance to S. America appears in this group, a single _Mycetopus_ occurring, the only species not Brazilian, while _Arconaia_ appears very closely to approach the _Hyria_ of the same locality. Several genera of the _Hydrobia_ type (_Pachydrobia_, _Jullienia_, _Chlorostracia_) are peculiar.

_Land and Fresh-water Mollusca of the Siamese Province_

Streptaxis 20
Ennea 3
Helicarion 7
Microcystis 3
Sesara (?) 1
Medyla 1
Xesta 4
Macrochlamys 6
Kaliella 5
Hyalinia (?) 1
Hemiplecta 14
Rhysota 2
Trochomorpha 6
Trochomorphoides 3
Plectopylis 5
Stegodera 2
Plectotropis 12
Trachia 3
Fruticicola 2
Acusta 2
Chloritis 8
Dorcasia 1
Camaena 5
Hadra 5
Obbina 1
Amphidromus 33
Bocourtia 2
Buliminus 4
Hypselostoma 2
Tonkinia 1
Clausilia 15
Opeas 7
Spiraxis (?) 2
Subulina 1
Succinea 4
Vaginula 7
Limnaea 7
Planorbis 6
Canidia 13
Melania 39
Faunus 1
Bithynia 9
Wattebledia 1
Stenothyra 4
Hydrobia 1
Pachydrobia 9
Jullienia 6
Lacunopsis 6
Chlorostracia 4
Vivipara 39
Valvata 1
Ampullaria 15
Assiminea 7
Procyclotus 6
Dasytherium 2
Opisthoporus 5
Rhiostoma 7
Myxostoma 1
Pterocyclus 7
Cyclophorus 28
Leptopoma 10
Lagochilus 6
Pupina 8
Hybocystis 3
Alycaeus 6
Cataulus (?) 1
Diplommatina 2
Helicina 4
Georissa 2
Modiola (f. w.) 2
Dreissensia 3
Anodonta 17
Mycetopus 1
Pseudodon 18
Dipsas 4
Unio 64
Arconaia 1
Cyrena 6
Batissa 1
Corbicula 35

(_c_) _The Malay Province_ includes the peninsula of Malacca south of Tenasserim, and the series of islands beginning with Sumatra and stretching eastward up to the Ké Is., besides Borneo and Celebes. The Philippines form a separate province.

The Malay province is singularly poor in representative forms, whether we regard it as a whole or consider the islands separately. Not a single genus, with the exception of _Rhodina_ (Malacca), appears to be peculiar. The contrast with the West Indies is in this respect very striking. Java, for instance, which is well explored, and almost exactly eleven times the size of Jamaica, has about 100 species of land Mollusca, while Jamaica has about 460.

This want of individuality in the land Mollusca of the Malay islands is accounted for by a consideration of the sea depths which separate them from the Asiatic mainland. The accompanying map, the red line on which is intended to show what would be the result of an elevation of the sea bottom for no greater amount than 100 fathoms, exhibits clearly the fact that these islands are practically a part of Asia, a large stretch of very shallow sea extending between Siam and the greater part of the north-west coast of Borneo.

In all probability the three great islands of Sumatra, Java, and Borneo were united with the mainland of Asia, and with one another, at a period, geologically speaking, comparatively recent. This follows from the general uniformity of their land Mollusca, both as regards one another and as regards the mainland. Nor do the smaller members of the island series--Bali, Lombok, Sumbawa, Flores, Timor, and Timor Laut--show any marked individuality in the possession of peculiar genera. Wallace’s line is absolutely non-existent, so far as the land Mollusca are concerned. The really noticeable break in distribution comes with the Aru Is., for while the Tenimber group (Timor Laut, etc.) are decidedly Malay, and the Ké Is., in the poverty of our information, uncertain, the Aru Is. are as Papuan as New Guinea itself. The profound depths of the Banda Sea to the north, and the Timor Sea to the south, appear to have kept the islands from Flores to Timor Laut free from the intrusion of any Moluccan or any considerable Australian element. The Moluccas, as has been already remarked, besides possessing considerable peculiarities of their own, unite a mixture of the Malay and Papuan elements, and serve as a sort of debatable ground for the meeting of the two.

The Malay peninsula is practically another island of somewhat the same shape and general trend as Sumatra, and about one-half the size. Its general relations--and the remark applies to the great Sunda Islands as well--appear to be rather more with Burmah, Tenasserim, and even the Cingalese district, than with Siam. Points of connexion between Ceylon and Sumatra, and Ceylon and Borneo, have already (p. 304) been brought out.

Map to illustrate the
GEOGRAPHICAL DISTRIBUTION
of the Land Mollusca of the
EAST INDIAN ARCHIPELAGO

_The red line marks the 100 fathom line_

London: Macmillan & Co. _London Stanford’s Geog^l. Estab^t_.]

It seems not impossible, from the point of view of the land Mollusca only, that the Sunda Islands may at one time have stretched much farther into the Bay of Bengal, prolonged, perhaps, into what are now the Andaman and Nicobar groups, while Ceylon and the western side of the Deccan, united into one continuous piece of land, and possibly separated from N. India by a wide stretch of sea, extended farther eastward in a long island, or series of islands.

Java, from its Mollusca, does not appear to hold the comparatively isolated position which its mammals and birds seem to indicate. Borneo, on the other hand, is more Siamese than Java or Sumatra in respect of a group whose metropolis is Siam, namely, the tubed operculates; for while that section is represented by 3 species in Sumatra and only 2 in Java, in Borneo it has as many as 19, _Rhiostoma_ not occurring in the two former islands at all. _Alycaeus_, _Lagochilus_, _Pupina_, and _Cyclophorus_ are found throughout, but _Hybocystis_ (Malacca, 1 sp.) does not quit the mainland. Borneo is remarkably rich in land operculates, especially noticeable being the occurrence (11 sp.) of _Opisthostoma_ (Fig. 208), a most extraordinary form of land shell (Ceylon, Siam), of _Diplommatina_ (17 sp.), and _Raphaulus_. The occurrence of a single _Papuina_ (Moluccas eastward) is very remarkable.

_Amphidromus_ is a genus characteristic of the great Sunda Islands, attaining its maximum in Java (12 sp.). The Indian _Glessula_ still has one species each in Sumatra, Java, and Borneo. One species of _Streptaxis_[369] occurs in Malacca, but _Ennea_ (3 sp.) reaches as far east as Borneo and the Philippines. _Parmarion_, _Helicarion_, _Ariophanta_, and other groups of the Naninidae are well represented. _Hemiplecta_ and _Xesta_ are abundant and large, while the _Rhysota_ of Borneo contain some huge sinistral forms. _Rhodina_ is a remarkable form from Malacca, whose exact generic position is not yet settled. _Clausilia_ has a few species on all the islands, the last occurring on Ternate, and a single _Papuina_ (Moluccas and N. Guinea) occurs in Borneo.

The _Island of Celebes_ marks the beginning of a distinct decrease in the Indo-Malay element. The Naninidae lose ground, in proportion to the Helicidae, _Macrochlamys_, for instance, being represented by only one species, and _Hemiplecta_ by four. Other characteristic genera of the Indian region dwindle, such as _Amphidromus_, _Clausilia_, the tubed operculates, and _Cyclophorus_, while _Sitala_, _Kaliella_, _Glessula_, and _Plectotropis_ disappear altogether. Comparing the total numbers of Naninidae and Helicidae from Sumatra to New Guinea, we obtain this interesting result:--

Sumatra Java Borneo Celebes Moluccas N. Guinea _Nanina_ (all genera) 26 32 51 22 36 40 _Helix_ (all genera) 7 11 13 14 55 91

It will be noticed that the proportion of Naninidae to Helicidae, which has been nearly 4 to 1 in Sumatra, falls to 3 to 1 in Java, and rises again to 4 to 1 in Borneo (showing the essentially continental character of the island); in Celebes it further falls to 3 to 2, while in the Moluccas the scale turns and _Helix_ has the advantage by about 8 to 5, and in N. Guinea by more than 2 to 1.

There is the same absence of marked features of individuality in Celebes as in the islands dealt with above. Not a single genus is peculiar. The nature of the sea bottom between Borneo and Celebes, with its indications of a somewhat broad bridge over an otherwise deep channel of separation, would seem to account for and suggest the true explanation of the facts as they stand. At the same time, there are indications of a certain amount of contrast between N. and S. Celebes. The Indian element, which constitutes the preponderating majority of the fauna, is common to north and south alike. But the north part of the island, in which _Obba_ and _Obbina_ occur, shows decided relationship with the Philippines, while the occurrence of three _Chloritis_ and one _Planispira_ tend to approximate S. Celebes rather with the Moluccas.

The _islands eastward of Java_, from Bali to Timor Laut and the Tenimber Is., present no trace of individual peculiarities; they simply carry on the Indo-Malay fauna as though along a great peninsula. Even Timor, surrounded as it is on all sides by sea of profound depth, shows no sign of possessing even one peculiar genus. _Amphidromus_, perhaps the most characteristic of all Indo-Malay genera, occurs throughout, diminishing in numbers as we go eastward (Bali, Lombok, and Sumbawa 4 sp., Timor 2 sp., Timor Laut 1 sp.), while _Plectotropis_ reaches no farther than Flores and Timor. The tubed operculates are altogether wanting. In Timor Laut we have Moluccan influence appearing in 3 _Chloritis_, and there is one (supposed) _Corasia_. Two _Helices_ of a marked Australian type (_Rhagada_) occur, one in Flores, the other on Dama I., south-west of Timor. The configuration of the sea bottom (see map) would lead us to believe that the north-west coast of Australia once stretched a good deal nearer to these islands.

The _Moluccas_, taken as a whole, constitute a transition region between the Indo-Malay and the Papuan faunas, uniting, to a very considerable extent, the features of both. They fall into two well-defined groups. The northern, or Ternate group, consists of Gilolo (Halmahera), Batchian, and the outlying islands as far south as and including Obi major. The southern, or Amboyna group, consists of Buru, Ceram, Amboyna, and the chain of islands to the south-east of Ceram, as far as, and including the Ké Is.

The Ternate group shows decidedly closer relations with New Guinea than the Amboyna group. Thus, among the _Helices_, the markedly Papuan genus _Papuina_ is represented by 7 species in the Ternate group, but by 1 in the Amboyna group. Again, the _Cristigibba_ section of _Planispira_, which is a Papuan form, has 4 representatives in the northern group, but only 1 in the southern. Certain points of connexion with Celebes come out in the southern group which are wanting in the northern; thus of _Chloritis_ there are 8 species in Amboyna, 0 in Ternate, 3 in Celebes.

In the Moluccas the Helicidae, for the first time as we move eastward from India, gain the ascendancy over the Naninidae, the numbers being, _Helix_ 55, _Nanina_ 36. If we take the groups separately, we find that in the Amboyna group the proportion is 22 to 23, while in the Ternate group it is 33 to 13, an additional proof that the Amboyna group is far less Papuan than the Ternate. Of _Planispira_, the most characteristic sub-genus of _Helix_, there are 12 species in the Ternate group, and 5 in the Amboyna. The section _Phania_, which contains 4 species of the finest _Helices_ known, is quite peculiar to the Ternate group. One species of _Obbina_, a sub-genus markedly Philippine, occurs in each group. Several of the Indo-Malay land operculates (_e.g._ _Ditropis_) reach their limit here, and here too we have the last _Clausilia_ (strangely absent from the Amboyna group). _Amphidromus_ is not reported on sufficient authority to warrant its insertion in the list.

_Land Mollusca of the Moluccas._ (T = Ternate, A = Amboyna[370] group)

Helicarion 1 A
Euplecta 1 A
Xesta 6 A, 4 T
Macrochlamys 1 A
Lamprocystis 4 A, 2 T
Macrocycloides 4 A
Sitala 1 A
Kaliella 3 A, 1 T
Trochomorpha 3 A, 3 T
Endodonta 1 A
Patula 1 A
Plectotropis 1 T
Eulota 1 A
Chloritis 8 A
Planispira 5 A, 12 T
Cristigibba 1 A, 4 T
Obbina 1 A, 1 T
Phania 4 T
Albersia 3 T
Camaena 1 T
Papuina 1 A, 7 T
Pupa 3 A
Vertigo 2 A
Clausilia 1 T
Opeas 4 A, 4 T
Subulina 1 A
Tornatellina 1 A
Vaginula 1 A
Melania 18 A, 4 T
Faunus 1 A
Vivipara 1 A
Acmella 1 A
Diplommatina 4 A, 2 T
Registoma 1 T
Pupinella 1 A
Callia 2 A
Leptopoma 4 A, 5 T
Lagochilus 1 A, 1 T
Ditropis 3 A
Cyclotus 4 A, 6 T
Omphalotropis 3 A
Georissa 1 T
Helicina 6 A, 3 T

(_d_) _The Philippine Province._--In the extraordinarily rich development of their Mollusca, the Philippines form a remarkable contrast with the poverty of the adjacent Malay islands. No less than 727 species of land Mollusca alone are known from the group, amongst which are included some of the finest and handsomest forms yet discovered. The main features of the fauna are Indo-Malay, with the addition of a certain Australasian element, and a remarkable development of individual characteristics.

The principal indigenous feature is the profuse abundance of the genus _Cochlostyla_, a group of large and elegant land shells, partly helicoid, partly bulimoid in shape, many of the species of which are covered with a curious hydrophanous epidermis. They are in the main of arboreal habits, living in the tops of the enormous forests which cover the greater part of the islands. As many as 247 species, belonging to 15 sub-genera, have been described.

The distribution of the sub-genera of _Cochlostyla_ on the different islands of the Philippine group affords important evidence on the geological relation of the islands to one another. Thus we find _Orthostylus_ and _Hypselostyla_ occurring in the central islands and S. Luzon, but not in Mindanao or Mindoro; we find _Chrysalis_ peculiar to Mindoro, _Prochilus_ to Mindoro and the Cuyos, _Ptychostyla_ to Luban, all these being sub-genera of very marked characteristics. Six out of the fifteen sub-genera are entirely absent from Mindanao, although occurring on the islands in the immediate vicinity. The little group Tablas-Romblon-Sibuyan are entirely deficient in certain sub-genera which occur on the islands surrounding them on all sides.[371]

Other forms peculiar to the Philippines are _Diaphora_, a section of _Ennea_ with a curiously produced mouth, and several sub-genera of the Naninidae (_Vitriniconus_, _Vitrinoidea_, _Hemitrichia_). The great _Rhysota_ here find their metropolis. Another very marked group of _Helix_ is _Obbina_, 19 of the 25 known species being peculiar.

The Helicidae proper of the Philippines are still held in check, as in the greater part of the Indian region, by the Naninidae. The single _Trachia_ and _Plectotropis_, and the 2 species each of _Plectopylis_ and _Satsuma_, indicate affinities with Indo-China. Further important Indian relationships are seen in the great _Nanina_ and _Cyclophorus_, which here attain almost Indian dimensions; in _Kaliella_ (8 sp.), _Sitala_ (2), _Clausilia_ (1). Among the operculates we still have 1 _Alycaeus_ and 1 _Coptochilus_. Singularly enough, several Indian genera which occur here are not found in the intervening islands of Borneo, Sumatra, or Java, _e.g._ _Streptaxis_, _Hypselostoma_, _Ditropis_, _Acmella_, and _Cyathopoma_. The curiously tubed Malay operculates, _Opisthoporus_, etc., fail to reach the Philippines proper, although occurring in Borneo and N. Celebes; one of them reaches Palawan. The strikingly Malay genus _Amphidromus_ reaches Palawan, but no farther (1 sp.), while 2 species reach Mindanao, and one of these penetrates as far as Bohol and S. Leyte. Amongst the slugs, _Mariaella_ occurs again only in the Seychelles, and _Tennentia_ only in Ceylon.

_Land and Fresh-water Mollusca of the Philippines_

Streptaxis 1
Ennea 10
Mariaella 3
Tennentia 1
Helicarion 21
Vitrinopsis 5
Vitrinoidea 1
Rhysota 17
Trochonanina 2
Euplecta 28
Hemiplecta 11
Hemitrichia 15
Xesta 2
Macrochlamys 5
Microcystis 3
Lamprocystis 17
Bensonia 4
Vitriniconus 16
Sitala 2
Kaliella 8
Trochomorpha 21
Endodonta 1
Plectopylis 3
Plectotropis 1
Aulacospira 3
Pupisoma 1
Satsuma 2
Dorcasia 2
Chloritis 7
Obbina 19
Papuina 1
Phoenicobius 7
Cochlostyla 247
Amphidromus 2
Hapalus (?) 4
Hypselostoma 1
Pupa 4
Clausilia 1
Subulina 3
Prosopeas 2
Opeas 4
Geostilbia 1
Tornalellina 1
Succinea 3
Vaginula 2
Ancylus 1
Limnaea 3
Planorbis 3
Physa 2
Melania 50
Pirena 2
Bithynia 1
Vivipara 7
Ampullaria 5
Acmella 2
Diplommatina 41
Arinia 6
Pupina 5
Registoma 7
Hargreavesia 1
Callia 2
Pupinella 3
Helicomorpha 4
Coptochilus 1
Alycaeus 1
Leptopoma 42
Lagochilus 11
Cyclophorus 31
Ditropis 7
Cyathopoma 5
Cyclotus 19
Omphalotropis 3
Helicina 18
Georissa 3
Anodonta 1
Cyrena 3
Corbicula 7

_Islands adjacent to the Philippines._--The Philippines are connected with Borneo by two distinct ridges or banks of elevation, which enclose between them the Soo-loo or Mindoro Sea. There can be little doubt that these ridges represent the ancient highway of transit, by which Indo-Malay species passed into the Philippines. The depth of the sea on either side is profound, ranging from an average of about 1000 fathoms west of Palawan to 2550 off the south-west coast of Mindanao.

It appears that the fauna of the Soo-loo ridge is definitely Philippine up to and including Bongao, Sibutu, and Bilatan, the last islands at the Bornean end of the ridge. On these are found two species of _Cochlostyla_ and an _Obbina_.

The Palawan ridge may also be described as more or less Philippine throughout. One species of _Cochlostyla_ occurs on Balabac, just north of Borneo, and two on Palawan, but these are perhaps counterbalanced by the definitely Indo-Malay _Amphidromus_ and _Opisthoporus_ (1 sp. each). At the northern end of the ridge, on Busuanga and Calamian, the Philippine element predominates.

Representatives of two remarkable groups of _Helix_ (_Camaena_ and _Phoenicobius_) occur along the Palawan ridge and in Mindoro. The _Phoenicobius_ find their nearest allies in the curious small group known as _Obba_, from N. Celebes, the _Camaena_ possibly in a type of _Helix_ (_Hadra_) occurring in New Guinea and N.E. Australia. The only other _Helix_ from the whole of the E. Indies which bears any resemblance to the _Phoenicobius_ group is _H. codonodes_ Pfr., which is peculiar to the Nicobars. A few forms assigned to _Camaena_ also occur in Further India and Siam. It would appear possible, therefore, that these two isolated groups are a sort of survival of a fauna which perhaps had once a much more extended range.

(2) The =Chinese Sub-region=.--The _Chinese Sub-region_ includes the whole of China from its southern frontier up to and including the basin of the Blue or Yang-tse River, together with the coast district, including Corea, perhaps as far north as Vladivostok, and the outlying islands of Hainan, Formosa, the Loo-Choo and Bonin groups, and Japan to the north of Niphon. It may be divided into two provinces, the Chinese and the Japanese.

(_a_) The fauna of the _Chinese province proper_ bears, in many respects, strong marks of relationship to that of India and Siam. Thus _Streptaxis_, _Helicarion_, _Macrochlamys_, _Kaliella_, _Sitala_, _Ariophanta_, _Rhysota_, _Hemiplecta_, _Diplommatina_, _Opisthoporus_, _Pterocyclus_, _Lagochilus_, and _Alycaeus_ all occur, especially in Southern China. The two points in which the sub-region bears special marks of individuality are _Helix_ and _Clausilia_. The sub-genera of _Helix_ which have their metropolis in China are _Satsuma_, _Cathaica_, _Aegista_, _Acusta_, _Euhadra_, _Plectotropis_, and _Plectopylis_. Sinistral forms (compare Fig. 213) are rather prevalent. In several cases--_e.g._ _Trichia_, _Gonostoma_, _Fruticicola_--there is a reappearance of forms which appear to belong to well-known European sub-genera. _Clausilia_ here attains a kind of second centre of distribution, and is represented by its finest forms, which belong to several peculiar sub-genera. The carnivorous Mollusca are not abundant, and are represented by _Rathouisia_ (a peculiar genus of naked slug), _Ennea_, and _Streptaxis_. In the western provinces _Buliminus_ is abundant in several sub-genera, one of which appears to be the European _Napaeus_.

There is little which is striking in the operculates, which are most abundant in the south, and appear to be mainly derived from Indian and Siamese sources. The occurrence of _Helicina_ (3 sp.), _Omphalotropis_ (1), _Leptopoma_ (2), and _Realia_ (2), is evidence of some influence from the far East. _Heudeia_ is a very remarkable and quite peculiar form of _Helicina_ with internal plicae, perhaps akin to the Central American _Ceres_.

Fresh-water genera are exceedingly abundant, especially _Melania_, _Unio_, and _Anodonta_. The occurrence of _Mycetopus_ (a South-American genus) is remarkable. There are several peculiar forms of fresh-water operculates, whose exact position is hardly yet assured.

_Land and Fresh-water Mollusca of the Chinese Province_

Rathouisia 1
Streptaxis 7
Ennea 12
Parmarion 2
Helicarion 15
Euplecta 3
Macrochlamys 19
Microcystina 2
Microcystis 7
Kaliella 16
Sitala 8
Ariophanta 1
Rhysota 5
Hemiplecta 1
Trochomorpha 2
Limax 1
Philomycus 1
Patula 2
Gonostoma 4
Metodontia 2
Vallonia 1
Plectotropis 9
Fruticicola 11
Satsuma 14
Trichia 10
Cathaica 22
Aegista 10
Armandia 3
Acusta 15
Obbina 1
Camaena 5
Euhadra 14
Plectopylis 19
Stegodera 6
Chloritis 1
Hel. Inc. sed. 39
Buliminus 21
Buliminopsis 3
Buliminidius 3
Napaeus 14
Rachis (?) 4
Pupa 10
Clausilia 102
Opeas 12
Euspiraxis 1
Subulina 5
Stenogyra (?) 12
Succinea 8
Vaginula 7
Limnaea 2
Planorbis 6
Melania 44
Paludomus 3
Bithynia 12
Lithoglyphus 3
Melantho (?) 1
Pachydrobia 1
Prososthenia 2
Stenothyra 2
Hydrobia 2
Mecongia 1
Oncomelania 9
Margaracya 1
Rivularia 4
Delavaya 1
Fenouillia 1
Vivipara 34
Diplommatina 20
Pupina 6
Alycaeus 23
Leptopoma 2
Lagochilus 10
Cyclophorus 18
Coelopoma 1
Pterocyclus 3
Opisthoporus 4
Cyclotus 10
Scabrina 4
Ptychopoma 12
Omphalotropis 1
Realia 2
Pseudopomatias 1
Helicina 3
Georissa 4
Heudeia 1
Cyclas 1
Corbicula 50
Unio 53
Monocondylaea 1
Anodonta 55
Mycetopus 12
Pseudodon 1
Dipsas 4

The island of _Hainan_, in the extreme south of the sub-region, has 40 species of Mollusca, 22 of which are peculiar, but there is no peculiar genus.

The Mollusca of _Formosa_, although in many cases specifically distinct, show close generic relationship with those of China. The characteristic Chinese groups of _Helix_ and _Clausilia_ occur, and there is still a considerable Indian element in several species of _Streptaxis_, _Macrochlamys_, _Kaliella_, and _Alycaeus_. The occurrence of two _Amphidromus_, a genus which, though Siamese, is not found in China or Hainan, is remarkable.

The peninsula of _Corea_ must undoubtedly be included in the Chinese sub-region. It is true that the land operculates scarcely occur, but there are still a number of _Clausilia_, and several of the characteristic Chinese groups of _Helix_ are reproduced. In some points Corea appears to show more affinity to Japan than to China, four of the _Helices_ being specifically identical with those of Japan, but the peninsula is at present too little explored for any generalisations to be made as to its fauna in this respect.

(_b_) _Japanese Province._--Kobelt distinguishes four groups of Mollusca inhabiting Japan (_a_) circumpolar species, actually occurring in Europe, Siberia, or N. America, or represented by nearly allied species (these of course do not belong to the Japanese province as such); (_b_) Indo-tropical species; (_c_) species which are Chinese or akin to Chinese; (_d_) peculiar species, a mixture of two forms, southern and northern, the latter being chiefly _Hyalinia_, _Patula_, and _Fruticicola_. Out of a total of 193 Japanese species, at least 164 are peculiar.

The Japanese _Helices_ belong to sub-genera common to China (_Plectotropis_ 8, _Euhadra_ 21, _Acusta_ 23?); but the Naninidae scarcely occur at all. The principal feature of the fauna is the development of _Clausilia_, which presents some extraordinarily fine forms. One slug (_Philomycus_) is identical with an Indian species. The operculates, which consist mainly of a few species each of _Diplommatina_, _Cyclophorus_, _Pupinella_, _Pupina_, _Helicina_, and _Georissa_, belong almost exclusively to the southern islands Kiu-siu, Sikoku, and southern Niphon. The three species usually reckoned as _Japonia_ are probably forms of _Lagochilus_.

=C. The Australasian Region=

This region includes all the islands of the Pacific east of the Moluccas, and falls into three sub-regions--the Papuan, the Australian, and the Polynesian.

1. The =Papuan Sub-region= may be divided into--(_a_) the _Papuan Province_ proper, which includes New Guinea, with the Aru Is. and Waigiou, the Admiralty Is., New Ireland, New Britain, and the d’Entrecasteaux and Louisiade Groups; (_b_) the _Queensland Province_, or the strip of N.E. Australia from C. York to the Clarence R. (about 29° S. lat.); (_c_) the _Melanesian Province_, which includes the New Hebrides, New Caledonia, with the Loyalty Is. and the Viti Is. The Solomons form a transition district between the Papuan and Melanesian provinces, abounding on the one hand in characteristic Papuan _Helices_, while on the other they form the north-western limit of _Placostylus_, the group especially characteristic of the Melanesian province.

(_a_) _The Papuan Province._--The molluscan fauna of New Guinea is the richest and by far the most original of all the Australasian region. We find ourselves, almost in a moment, in a district full of new and peculiar forms. New Guinea may be regarded as the metropolis of the rich Helicidan fauna, which is also characteristic of the Moluccas to the west, of N. and N.E. Australia to the south and south-east, and of the Solomons and other groups to the north-east. Here abound species of _Papuina_ and _Insularia_ (the latter being quite peculiar), among which are found, if not the largest, certainly the most finished forms of all existing _Helices_. _Chloritis_ (13 sp.), _Planispira_ (5), and _Cristigibba_ (9) are common with the Moluccas, while a tropical Australian element is shown in _Pedinogyra_ (1) and _Hadra_ (4). Very remarkable, too, is the occurrence of one species of _Obbina_ and _Rhysota_, genera which culminate in the Philippines and here find their most eastward extension; while a single _Corasia_ serves to form a link between the _Corasia_ of the Philippines and those of the Solomon Is., if the latter are true _Corasia_.

We naturally find considerable traces of a Polynesian element, which appears to be principally characteristic of the eastern part of the island. Most noteworthy in this respect is the occurrence of _Partula_ (3), _Tornatellina_ (1), _Charopa_ (1), _Thalassia_ (3). As compared with the true _Pulmonata_, the operculates are feebly represented, and the great majority are of a markedly Polynesian type. Not a single _Cyclophorus_ occurs; _Lagochilus_, _Alycaeus_, and all the tubed operculates, so marked a feature of the Indo-Malay fauna, are conspicuous by their absence, and the prevailing genera are _Cyclotus_, _Helicina_, and a number of sections of _Pupina_. _Leptopoma_, as in the Philippines, is strongly represented. Not that an Indo-Malay element is altogether absent. We still have _Xesta_ (5), _Hemiplecta_ (8), and even _Sitala_ (2), but the great predominance of _Helix_ seems to have barred the progress, for the greater part, of the Indian Naninidae.

The slugs appear to be represented by a solitary _Vaginula_. A single _Perrieria_ is a very marked feature of union with Queensland, where the only other existing species (_P. australis_) occurs. The solitary _Rhytida_, so far the only representative of the carnivorous group of snails, emphasises this union still further. Little is known of the fresh-water fauna. _Melania_ (28 sp.) is predominant, but on the whole the relations are Australian rather than Indo-Malay. _Ampullaria_ is wanting, while a decisive point of similarity is the occurrence of _Isidora_ (3 sp.), a genus entirely strange to the Oriental region, but markedly characteristic of the Australasian.

_Land and Fresh-water Mollusca of New Guinea_

Rhytida 1
Helicarion 2
Rhysota 1
Hemiplecta 11
Xesta 2
Microcystis 3
Microcystina 2
Sitala 2
Oxytes (?) 2
Conulus 1
Trochomorpha 8
Nanina (?) 3
Charopa 1
Thalassia 3
Ochthephila(?) 1
Chloritis 13
Planispira 5
Cristigibba 9
Insularia 17
Obbina 1
Albersia 3
Hadra 4
Pedinogyra 1
Papuina 35
Corasia (?) 1
Bulimus (?) 1
Calycia 4
Partula 3
Pupa 1
Stenogyra 1
Tornatellina 1
Perrieria 1
Succinea 1
Vaginula 1
Limnaea 2
Isidora 3
Melania 28
Faunus 1
Vivipara 4
Diplommatina 1
Pupina 4
Pupinella 3
Omphalotropis 2
Bellardiella 2
Leptopoma 16
Cyclotus 5
Cyclotropis 5
Helicina 15
Unio 4
Cyrena 3
Corbicula 1
Batissa 8

_Waigiou_ is practically a part of New Guinea. Twelve genera and twenty species of Mollusca are known, eight of the latter being peculiar. The occurrence of _Papuina_, _Insularia_, and _Calycia_ sufficiently attest its Papuan relationship. Two species each of _Albersia_, _Chloritis_, and _Planispira_ occur.[372]

The _Aru Is._ are, as we should expect from their position, and particularly from the configuration of the adjacent sea bottom (see map), markedly Papuan. At the same time they show unmistakable signs of long-continued separation from the parent island, for of their 36 land Mollusca 15, and of their 20 fresh-water Mollusca 9 are peculiar. The Papuan element consists in the presence of _Papuina_, _Albersia_, and _Cristigibba_. Moluccan influence is not absent, for the three _Helicina_, the _Albersia_, and one _Cyclotus_ are all Moluccan species. The fresh-water fauna appears to be a mixture of varied elements. The single _Segmentina_ is common to India, the _Glaucomya_ to Malacca and the Philippines, while the single _Batissa_ is also found in New Zealand.

_Land and Fresh-water Mollusca of the Aru Islands_

Xesta 4
Microcystis 1
Hyalinia(?) 1
Trochomorpha 1
Patula 1
Eulota 1
Chloritis 5
Cristigibba 2
Albersia 1
Papuina 4
Pupa 2
Stenogyra 2
Planorbis 1
Segmentina 1
Melania 14
Leptopoma 3
Moussonia 1
Realia 1
Cyclotus 3
Helicina 3
Cyrena 2
Glaucomya 1
Batissa 1

The _Louisiades_, the _d’Entrecasteaux_, and _Trobriand Is._, and _Woodlark I._, are closely related to New Guinea, containing no peculiar genera. Each group, however, contains a considerable proportion of peculiar species, an indication that their separation from New Guinea dates from a very distant period. From the Louisiades are known 34 species in all, 22 of which are peculiar.

The fauna of the _Admiralty Is._, of _New Hanover_, and _New Ireland_ is markedly Papuan, without any especial feature of distinction. The Admiralty Is. contain 15 sp. _Papuina_, 7 _Chloritis_, 1 _Planispira_, and 1 _Corasia_. A single _Janella_ shows relationship with the New Hebrides and with New Zealand. In New Ireland _Planispira_ (which is specially characteristic of W. New Guinea and the Moluccas) has disappeared, but there are 7 _Papuina_ and 6 _Chloritis_. The essentially Polynesian _Partula_ is present in both groups.

The prominent feature of the Mollusca of the _Solomon Is._ is the extraordinary development of _Papuina_, which here culminates in a profusion of species and singularity of form. The genus is arboreal, crawling on the branches and attaching itself to the leaves of trees and underwood. Of the 140 land _Pulmonata_ known from the group, no less than 50, or 36 per cent, are _Papuina_. Ten species of _Corasia_ occur, but whether the shells so identified are generically identical with those of the Philippines, is not satisfactorily determined. _Trochomorpha_, with 22 species, here attains its maximum. _Chloritis_ begins to fail, but still has 3 species. Indo-Malay influence still appears, though feebly, in _Hemiplecta_ (3), _Xesta_ (1), and possibly even _Macrochlamys_ (1). The _Rhytida_, the 3 _Hadra_, and possibly the _Paryphanta_ represent the Australian element. The growing numbers of _Partula_ (13), the small and inconspicuous land operculates (only 22 in all, with _Helicina_ very prominent), and the almost complete absence of fresh-water bivalves, show signs of strong Polynesian affinities. An especial link with the New Hebrides, New Caledonia, and the Viti Is. is the occurrence of _Placostylus_ (16 sp.). It is very remarkable that this genus should occur in the Solomon Is. and not in New Ireland. The occurrence of _Streptaxis_, if authentic, is very noteworthy, the nearest species being from the Philippines.

_Land and Fresh-water Mollusca of the Solomon Islands_

Streptaxis (?) 1
Rhytida 1
Paryphanta (?) 1
Helicarion 2
Xesta 1
Macrochlamys 1
Hemiplecta 3
Microcystis 2
Trochomorpha 22
Nanina (?) 2
Patula 1
Thalassia 2
Chloritis 3
Philina 2
Hadra 3
Papuina 50
Merope 1
Corasia (?) 10
Placostylus 16
Partula 13
Succinea 1
Melania 18
Diplommatina 2
Pupina 4
Leptopoma 4
Omphalotropis 2
Cyclotus 1
Cyclotropis 2
Helicina 7
Unio 1

(_b_) _The Queensland Province._--The strip of coast-line from Cape York to the Clarence R. stands apart from the rest of Australia, and is closely connected with New Guinea. There can be little doubt that it has been colonised from the latter country, since an elevation of even 10 fathoms would create (see map) a wide bridge between the two. Many of the genera are quite strange to the rest of Australia. Land operculates are abundant, and of a Papuan type. Several of the characteristic Papuan genera of _Helix_ (_Papuina_, _Chloritis_, _Planispira_) occur, while _Hadra_ attains its maximum. _Panda_, _Pedinogyra_, and _Thersites_ are three remarkable groups in a rich _Helix_ fauna. _Parmacochlea_ is a peculiar form akin to _Helicarion_. The carnivorous Mollusca are represented by _Rhytida_, _Diplomphalus_ (New Caledonia), and _Elaea_. One species of _Janella_, a slug peculiar to this region, occurs. The predominant fresh-water genus is _Bulinus_ (_Isidora_). _Ampullaria_ and _Anodonta_ are entirely absent from Australia and New Zealand.

MAP
to illustrate the relations
OF THE LAND MOLLUSCA OF
NEW GUINEA WITH THOSE
OF NORTH AUSTRALIA.

_The red line marks the 100 fathom line_

London: Macmillan & Co.]

_Land Mollusca of the Queensland Province_

Diplomphalus 1
Rhytida 10
Elaea 1
Parmacochlea 1
Helicarion 7
Nanina 3
Hyalinia 10
Thalassia 4
Charopa 5
Patula (?) 4
Macrocyclis (?) 1
Helicella 10
Planispira 8
Hadra 51
Chloritis 5
Pedinogyra 1
Thersites 1
Papuina 6
Panda 2
Helix (inc. sed.) 6
Bulimus (?) 1
Stenogyra 1
Tornatellina 4
Pupa 3
Vertigo 4
Perrieria 1
Succinea 3
Vaginula 1
Janella 1
Georissa 1
Pupina 16
Hedleya 1
Callia 1
Diplommatina 3
Ditropis 2
Dermatocera 1
Helicina 8

(_c_) _The Melanesian Province_ includes those islands on which the remarkable group _Placostylus_ occurs, the metropolis of whose distribution is New Caledonia. These islands are very possibly the remains of what was once a much wider extent of land. A single species of _Placostylus_ occurs both on Lord Howe’s I. and in the North I. of New Zealand, but this fact, while highly interesting as indicating a possible former extension of land in a south-easterly direction, is hardly sufficient to bring these islands within the province as now limited. The Solomon Is., although containing _Placostylus_ as far to the west as Faro I., form, as has been already stated, a transitional district to the Papuan province.

_New Caledonia._--The chief features of the Mollusca are the remarkable development of the helicoid carnivorous genera _Rhytida_ (30 sp.) and _Diplomphalus_ (13 sp.), and of _Placostylus_ (45 sp.). There is a stray _Papuina_, and a peculiar form _Pseudopartula_, but _Helix_ has almost entirely disappeared. Polynesian influence is represented by _Microcystis_ (3 sp.), the so-called _Patula_ (13 sp., many of which are probably _Charopa_), _Tornatellina_ (2 sp.), and _Helicina_ (20 sp.). _Partula_ does not reach so far south, but there are two species of _Janella_. The recurrence of _Melanopsis_ (19 sp.), absent from the whole Oriental region, is curious, and forms another link with New Zealand. The curious sinistral _Limnaea_ (_Isidora_), common with Australia and New Zealand, is abundant.

_The New Hebrides_ link New Caledonia and the Solomons by their possession of the typical heavy _Placostylus_ (5 sp.) of the former, and the lighter and more elegant _Charis_ (2 sp.) of the latter. There are 4 _Papuina_, and _Partula_ is abundant (18 sp.), but there is no evidence at present that the carnivorous genera or the _Melanopsis_ and _Isidora_ of New Caledonia occur.

_The Fiji Is._, by the possession of 14 _Placostylus_ of the _Charis_ section, which is entirely absent from the adjacent Tonga group, form the eastern limit of the province. There appears to be only a single _Partula_, but the Polynesian element, especially as seen in _Navicella_ (8 sp.), _Neritina_ (20 sp.), _Helicina_ (11 sp.), and _Omphalotropis_ (11 sp.), is very strong. The _Microcystis_ (9 sp.) and _Trochomorpha_ (14 sp.) are also of a Polynesian type.

(2) The =Australian Sub-region= includes the whole of Australia (with the exception of the Queensland province) and Tasmania, with New Zealand and the off-lying islands. The fauna, from the prevalence of desert, is scanty, especially in genera. Land operculates are almost entirely wanting. _Limax_ is not indigenous, though several species have become naturalised. The bulk of the fresh-water species belong to _Isidora_, and it is doubtful whether _Physa_ occurs at all. _Unio_ has a few species, and also _Vivipara_, but neither _Anodonta_ nor _Ampullaria_ occur. There are a few _Melania_ and _Neritina_.

_Tropical South Australia._--The Mollusca are scanty, and occur chiefly in the neighbourhood of the rivers, the soil being arid, with no shelter either of trees or rocks. Fresh-water species predominate, and the rich land fauna of Queensland is totally wanting. There are no land operculates, 6 _Hadra_, 1 _Bulimus_ (?), 1 _Stenogyra_.

_West Australia._--Owing to the deserts which bound it, the Mollusca are very isolated, only one species being common with N., S., and E. Australia. The chief characteristics are _Liparus_, a form intermediate between _Helix_ and _Bulimus_, and, among the _Helices_, the group _Rhagada_. There are no slugs, no carnivorous snails, and only three land operculates.

_Land Mollusca of West Australia_

Lamprocystis 1
Hyalinia 1
Patula 7
Chloritis 2
Gonostoma 2
Trachia 3
Xerophila 1
Rhagada 8
Hadra 5
Liparus 10
Pupa 4
Succinea 3
Cyclophorus 2
Helicina 1

In _Eastern and Southern Australia_ (New South Wales, Victoria, and South Australia) the tropical element, so abundant in Queensland, almost entirely disappears, the last operculate (a _Helicina_) only reaching Port Macquarie, though several species of _Helicarion_ occur in the extreme south. _Hadra_ is still abundant in New South Wales (18 sp.) and S. Australia (10 sp.), but becomes scarce in Victoria (2 sp.); New South Wales has also one _Panda_ and two _Thersites_. _Cystopelta_ is common with Tasmania, and one of the Janellidae (_Aneitea_) with Queensland. The carnivorous snails are represented by _Rhytida_. _Caryodes_, a bulimoid group perhaps akin to _Liparus_, is common with Tasmania only.

_Tasmania._--About 80 species of land Mollusca are known, not more than 10 being common with Australia. No land operculates occur; _Endodonta_ and _Charopa_ are rare, and _Hadra_ has entirely disappeared, but _Pupa_ and _Succinea_ occur. Carnivorous genera are represented by _Paryphanta_, _Rhytida_, and _Rhenea_. _Anoglypta_ is a peculiar section of _Helix_, while _Caryodes_, _Cystopelta_, and _Helicarion_ are common with Australia. Among the fresh-water Mollusca are a _Gundlachia_ (see p. 345), and some forms of _Amnicola_ or _Hydrobia_, one of which (_Potamopyrgus_) is common only with New Zealand.[373]

_The Neozealanian Province._--The Mollusca of New Zealand, with the Kermadec, Chatham, and Auckland Is., are remarkably isolated. Such genera as _Nanina_, _Partula_, _Pupa_, _Stenogyra_, _Succinea_, _Vaginula_, _Truncatella_, _Helicina_, and _Navicella_, which might have been expected to occur, are entirely absent. The bulk of the land Mollusca are small and obscure forms, perhaps remains of a very early type, and appear to belong to the Zonitidae, neither _Patula_ nor _Helix_ occurring at all. The carnivorous forms are represented by _Schizoglossa_, a peculiar genus akin to _Daudebardia_, by _Paryphanta_, an extraordinary group of large shells with a thick leathery epidermis, and by _Rhytida_ and _Rhenea_. In spite of its extreme isolation, the general relations of the fauna are partly with New Caledonia, partly with E. Australia. The occurrence of _Placostylus_ has already been mentioned (p. 323), and three species of _Janella_, a genus which also occurs in Queensland and New Caledonia, indicate the same affinity. _Otoconcha_ is peculiar. The fresh-water Mollusca, besides the _Isidora_ characteristic of the sub-region, are partly related to New Caledonia through the occurrence of _Melanopsis_, partly to Tasmania through _Potamopyrgus_, while the peculiar _Latia_ is possibly akin to _Gundlachia_ (Tasmania). The land operculates number only 5 genera and 14 species in all, excluding a doubtful _Diplommatina_.[374]

_Land and Fresh-water Mollusca of the Neozealanian Province_

Schizoglossa 1
Paryphanta 5
Rhytida 6
Rhenea 2
Helicarion 1
Otoconcha 1
Microcystis 1
Trochonanina 1
Phacussa 3
Thalassohelix 5
Gerontia 2
Allodiscus 10
Pyrrha 1
Therasia 7
Phenacohelix 3
Suteria 1
Flammulina 13
Laoma 23
Endodonta 10
Charopa 28
Placostylus 1
Carthaea 1
Tornatellina 1
Janella 3
Latia 2
Ancylus 2
Limnaea 5
Amphipeplea 2
Planorbis 1
Isidora 7
Melanopsis 2
Potamopyrgus 4
Paxillus 1
Lagochilus 7
Omphalotropis 1
Realia 4
Hydrocena 1
Unio 9
Sphaerium 1
Pisidium 2

_Lord Howe’s I._ is remarkable as containing a _Placostylus_, which thus links the island with this province. The remainder of the fauna is Polynesian, with the exception of a species (common to the Fijis) of _Parmella_, a slug akin to _Helicarion_, _Parmacochlea_, and _Cystopelta_.

(3) The =Polynesian Sub-region= includes all the island groups of the central and southern Pacific (except those classified in the Papuan and Australian sub-regions), from the Pelews and Carolines in the west to the Marquesas and Paumotus in the east, and from the Tonga group in the south to the Sandwich Is. in the north. It may be subdivided into (_a_) the Polynesian province proper, and (_b_) the Hawaiian province, which includes the Sandwich Is. only.

(_a_) The general features of the _Polynesian province_ are very similar throughout, although the Mollusca of each island group are in the main peculiar. The species are mostly small and obscure. _Helix_ scarcely occurs, its place being taken by small Zonitidae (_Microcystis_, _Charopa_, _Trochomorpha_, etc.), and by groups of so-called _Patula_ (_Endodonta_, _Pitys_, etc.), the exact position of which is not yet settled. _Libera_, remarkable for its method of ovipositing (p. 128), is peculiar to the Society and Hervey Is.; _Partula_ is almost universal, attaining its maximum (40 sp.) in the Society Is.; _Tornatellina_, _Pupa_, and _Vertigo_ occur throughout.

The land operculates consist chiefly of _Omphalotropis_, _Pupina_, _Realia_, and _Helicina_. _Diplommatina_ and _Palaina_ are abundant on the Pelews, and a _Moussonia_ occurs in the Samoa Is. _Ostodes_, a small form of _Cyclophorus_, is found in some of the southern groups. The fresh-water operculates are _Melania_, _Neritina_ (including _Clithon_, a sub-genus furnished with spines), and _Navicella_; there are no Unionidae, while fresh-water _Pulmonata_ are very scarce.

(_b_) The land Mollusca of the _Hawaiian province_ are distinguished by the possession of four entirely peculiar genera--_Achatinella_, _Leptachatina_, _Carelia_, and _Auriculella_. More than 300 of the two former genera have been described, every mountain valley of some of the islands having its own peculiar species. The destruction of the indigenous herbage by goats is rapidly extinguishing many forms. _Partula_, and the small land operculates, so characteristic of the other groups, are, with the exception of _Helicina_, entirely wanting. The occurrence of one of the _Merope_ group of _Helix_ (Solomon Is.) is remarkable, and there is a rich development of _Succinea_. “_Patula_,” _Microcystis_, _Tornatellina_, and the other small Polynesian land _Pulmonata_ are well represented. The presence of _Isidora_, absent from the central Pacific groups, is remarkable, and _Erinna_ is a peculiar genus belonging to the Limnaeidae.