174 



SCIENCE-GOSSIP. 



ARMATURE OF HELICOIlJ LAXUSHELLS. 



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

 (Concluded from page 149.) 



A^yTTH regard lo the geographical distribution, as 

 far as our present ivnowledge enables us lo 

 judge, 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 map, where I have 

 indicated all the known species at their respective 



believe, who has traversed this region, informs me he 

 collected forms of Pleclopylis there, but I have not 

 yet been able to inspect them. Crossing the Hima- 

 layan Range we find one species in Eastern TiV^et, 

 P. alpkousi, while China, including Hongktjng, has 

 no less than seventeen species. A wide gap 

 separates the Sikkim forms from the South Indian 

 and the Cingalese species, a fact which \vill 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 Plectopvlis. 



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. andersoni, 

 one from Munipur, P. mmiipitrensis , and 

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

 P. ponsonhyi, and /'. woodlhoipei. 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 

 Nov. 1899— No. 66, Vol. VI. 



exploration will bring to light many additional 

 species, and possibl)^ both Siam and Cochin China 

 will, when they are searched diligently, be found to 

 posse.ss some interesting forms of the genus. 



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

 pylis are known. I omitted to «iention, however, 

 that Dr. Stoliczka described three species of fossil 

 Helices, which he referred to the section Anchistoma 

 = Gonostoma, stating that they had affinity with 

 Plectopylis and Gorilla. (Cretaceous Fauna of Southern 

 India, II., p. 9 et. sec/.). Mr. Nevill, who examined 

 the.se fo.ssil shells, on the other hand, was of opinion 

 that iheir appearance did not warrant this theory. 

 (Journ. A.siat. Soc. Beng. L., 1S81, p. 128). 



I append a key lo the species which I venture lo 

 hope will prove serviceable ; and. Um convenience of 

 reference, I have added an index. 



