174 



SCIENCE-GOSSIP. 



ARMATURE OF HELICOID LANDSHELLS. 



By G. K. GuDE, F.Z.S. 



{(Concluded front page 149.) 



T^yiTH regard to the geographical distribution, as 

 far as our present knowledge enables us to 

 udge, the genus is confined to Sikkim, Assam, Further 

 India and China, extending south to Tenasserim, 

 north as far as Central China, west to Sikkim, and 

 east to Tonkin, with two outlying groups : one in the 

 southern extremity of the Indian Peninsula and Ceylon, 

 the other in the Philippine Islands. 



On looking at the accompanying niap, where I have 

 ndicated all the known species at their respective 



believe, who has traversed this region, informs me he 

 collected forms of Phctopylis there, but I have not 

 yet been able to inspect them. Crossing the Hima- 

 layan Range we find one species in Eastern Tibet, 

 P. alphonsi, while China, including Hongkong, has 

 no less than seventeen species. A wide gap 

 separates the Sikkim forms from the South Indian 

 and the Cingalese species, a fact which will be less 

 surprising, if, as I suspect, the latter prove to belong 

 to a distinct genus. In all probability further 



Map, showing Distribution of Genus Plectopylis. 



habitats, some curious and striking facts in the distri- 

 bution of the genus Plectopylis become apparent. It 

 .will be seen that the centre of distribution appears to 

 be Lower Burma, especially Pegu and Tenasserim ; 

 while no species occur to the south-east, the whole 

 of Siam and Cochin China being blanks. Going east 

 the Burmese Shan States and Laos each possess one 

 species, P. shanensis and P. laomontana respectively, 

 while Tonkin has eight. Upper Burma contributes 

 one species from the Bhamo district, P. audersoni, 

 one from Munipur, P. mtinipurensis, and 

 three species in the south, i.e., P. perarcta, 

 P. ponsonliyi, and /-'. woodthorpei. Assam has 

 fourteen species. Going west we find another blank 

 till we reach Sikkim, the western limit of the genus, 

 where there are five species. The intervening 

 country, Bhutan, has scarcely been explored, but 

 Lieut. -Col. Godwin-Austen, the only naturalist, I 



exploration will bring to light many additional 

 species, and possibly both Siam and Cochin China 

 will, when they are searched diligently, be found to- 

 possess some interesting forms of the genus. 



On page 149 I stated that no fossil forms of Plecto- 

 pylis are known. I omitted to mention, however,, 

 that Dr. Stoliczka described three species of fossil 

 Helices, which he referred to the section Anchistoma, 

 =Gonostoma, stating that they had affinity with 

 Flectopylis and Gorilla. (Cretaceous Fauna of Southern 

 India, II., p. 9 el. set/.). Mr. Nevill, who examined 

 these fossil shells, on the other hand, was of opinion 

 that their appearance did not warrant this theory. 

 (Journ. Asiat. Soc. Beng. L., iSSi, p. 128). 



I append a key to the species which I venture to 

 hope will prove serviceable ; and, for convenience of 

 reference, I have added an inde 



