The Cambridge natural history . ient height to offer any effectivebarrier to distribution. The province is accordingly qualified toa considerable extent by Indian and Chinese elements. Streptaxis is, but for three Ennea, the sole representative ofthe carnivorous genera, and attains its maximum in the OldWorld. Partly owing to Chinese infiuence, the Helicidae, with11 genera and 46 species, begin to regain their position ascompared with the JSTaninidae (12 genera, 54 species). Of theHelicidae, Acusta and Hadra appear now for the first time, and,with Plectotrojns, Stegodera, and CUmsilia, form a
The Cambridge natural history . ient height to offer any effectivebarrier to distribution. The province is accordingly qualified toa considerable extent by Indian and Chinese elements. Streptaxis is, but for three Ennea, the sole representative ofthe carnivorous genera, and attains its maximum in the OldWorld. Partly owing to Chinese infiuence, the Helicidae, with11 genera and 46 species, begin to regain their position ascompared with the JSTaninidae (12 genera, 54 species). Of theHelicidae, Acusta and Hadra appear now for the first time, and,with Plectotrojns, Stegodera, and CUmsilia, form a marked Chinese element. Amjjhidromus,with 33 species, is the most char-acteristic land pulmonate. Severalgenera, whose nucleus of distribu-tion lies among the islands farthereast, appear to have penetrated asfar as these coasts. Such are Chlo-ritis, Camaena, and Ohhina amongthe Helicidae, Trochomorpha, and,of the operculates, Helicina. Land operculates are very richlydeveloped. In all, there are 17 genera and 104 species Fig. 206.—Cycloplwrus siamensisSowb., Siam. SIAM AND CAMBODIA 307 The tubed operculates attain their maximum, and Cyclophorusis even more abundant than in India. Fresh-water bivalvesabound. JDipsas and Fseudodon are common to China, and Unioand Anodonta are profusely represented. A curious resemblanceto S. America appears in this group, a single Mycetopus occurring,the only species not Brazilian, while Arconaia appears very closelyto approach the Hyria of the same locality. Several generaof the Hydrobia type {Pachydrolia, Jullienia, Chlorostracia) arepeculiar. Land and Fresli-water Mollusca of the Siamese Province Streptaxis . 20 Chloritis. 8 Faunus . 1 Leptopoma . 10 Ennea . . 3 Dorcasia. 1 Bithynia. 9 Lagochilus . G Helicarioii . 7 Camaena 5 Wattebledia 1 Pupina . 8 Microcystis . 3 Hadra . 5 Stenothyra . 4 Hybocystis . 3 Sesara (?) 1 Obbina . 1 Hydrobia 1 Alycaeus 6 Medyla . . 1 Anipludrouiu s33 Pacliydrobia 9 Cataulus (?). 1 Xesta . . 4 Bocourtia 2
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
