JOURNAL 
OF THE 
ASIATIC SOCIETY OF BENGAL. 
—_— 
Part II.—PHYSICAL SCIENCE. 
No. I.—1879. 
I.—On new species of the Genus Plectopylis of the Family Helicide.—By 
Lrevut.-Cotonet Gopwin-Austren, F. R. G. S., F. Z. S., &e., late 
Deputy Superintendent Topographical Survey of India. 
(Received October 7th, 1878 ;—Read March 5th, 1879.) 
(With Plate I.) 
Since the paper on the shells of this group of Helices was published 
in the Proceedings of the Zoological Society of London, Nov. 17th, 1874, I 
among a collection of shells made by Mr. O. Limborg, of which a list is 
being prepared ; the other two are from Eastern Assam. I give a plate, 
drawn with the aid of the camera lucida, shewing enlarged the arrangement 
- of the internal plice, which differ materially from all those I have as yet 
examined and figured ; these differences form the best of characters by which 
the species may be determined. Some conchologists may be inclined to 
doubt the persistence of these internal characters ; personal observation is, 
however, the best means of settling such a point. Having a very large 
number of P. brachydiscus, described below, I set to work and broke open 
42, specimens without finding the very slightest variation; of P. brakma 
thirteen were examined with the same result ; there is some slight variation 
_ in the young, but only in so far that the barriers shew an undeveloped state, 
the general arrangement being the same, In P. achatina, I found perfect 
similarity in some 12 specimens, and the result has been similar in all other 
= that I have examined. I think we may therefore feel certain 
that such internal structures, depending as they do on the form of the 
have had the good fortune to obtain three new species, one from Tenasserim, - 
ie 
