MOLLUSCA OE INDIA. 201 



strikes the dissector at once ; the clusters (fig. 3 c) are not unlike the 

 fruit of the banana, to give an idea of their form, given off from 

 a thin stem in paired gi'oups of 4-6 each. 



Geuiis Pleotopylis, Benson. 

 Ann. & Mag. Nat. Hist., 1860, vol. v. p. 2-14. 



The generic relationship of Plectopijlis has long been left for 

 further investigation. In fact, ever since Ferdinand Stoliezka, 

 thirty-six years ago *, described and figured the anatomy of the 

 animals of two species, P. acliatina (Gray) and P. cyclaspis, Bs., 

 and gave his views thereon, very little more has been done from a 

 morphological point of view. Conchologically, there is now little 

 more to be done beyond the description of species which are yet to 

 be found in the little-known parts of the countries east of Burmah 

 and the Assam Valley. Some years ago I was led to point out the 

 beautiful diversity of structure presented by the internal plication, 

 and it was my good fortune to collect and describe several fine new 

 forms t. This commencement left much still to be done, and I am 

 glad to say it has since been taken up and carried to a high degree 

 of excellence and completeness by the work, commencing with 

 Gorilla in 1896, of Mr. G. K. Gude, who, in a series of most inter- 

 esting papers published in ' Science Gossip,' 1896-99, entitled 

 " Armature of Helicoid Land-Shells," has shown the specific varia- 

 tion of every known species up to the present time. The greatest 

 credit is due to work of this nature, for the interest surrounding 

 this group of land-shells has been vastly increased. The animal 

 now requires investigation, and I shall begin by extracting all 

 the more important observations of Stoliezka. He commences by 

 saying, on p. 217 : — 



"The anatomy of the animal of Plectopylis indicates a good 

 generic distinction from allied forms. I cannot, however, say how 

 far the peculiarities, to which I shall presently refer, agree with 

 the Ceylonese Corilla, but a comparison of the two will no doubt 

 prove interesting and establish more firmly the relations of the 

 present genus to Corilla, Ophiogiira, and the American Polygi/ra. 

 .... I fully expect that when the animal of Helix retifera becomes 

 known, it will probably exhibit somewhat different characters from 



those of the present genus I consider these internal folds to 



be in some respect analogous to the clausilium in Clausilia, the 

 animals of the two genera being also somewhat similar in external 

 characters. When the animal of Plectopylis retracts into its shell, 



* Journ. Asiat. Soc. Beng. vol. xl. pt. 2, p. 217, pi. xv. figs. 1-6 (1871). 



t " Descriptions of five new Species of Helicidse of the Subgenus Plectopylis, 

 with Eeiiiarks on all the other known Forms," P. Z. S., Nov. 1874, p. 108, 

 pis. Ixxiii. & Ixxiv. 



