On two new Helicidse. 1G3 



out strictly and honestly, so far as in mc lies, the Rules set 

 forth by the British Association, and this without regard to 

 consequences. I only regret that the attempt involves so much 

 toil and waste of time ; hut I will not prolong these tedious 

 remarks on so trifling a subject ; I will only say, I have no 

 wish to be thought an infallible interpreter of those rules, and 

 that I am no believer in nomenclatural finality ; for I bear in 

 mind that the truthful lines are here applicable : — 



" Critics I saw that others' names efface, 

 And fix their own, with labour, in the place. 

 Their own, like others', soon their place resigned, 

 Or disappeared, and left the first behind." 



Magdalene College, Cambridge, 

 July 11, 1879. 



XIX. — Description of two new Species 0/ Plectopylis, a Sab- 

 genus of the Ileliciclce. By Lieut. -Colonel H. H. GODWIN- 

 Austen, F.Z.S. &c. 



Among some specimens of Plectopylis pinacis, Benson, of large 

 size from Darjiling, given me by Ferd. Stoliczka, are several 

 smaller shells which no doubt are referable to P. mcccromphalus, 

 W. Blf., var. minor, alluded to in the ' Journal of the Asiatic 

 Society of Bengal,' 1870, p. 18. Mr. Blanford shows that it 

 is quite distinct from pinacis, and, perhaps not having mature 

 specimens of this Darjiling shell, considered it the same as the 

 Khasi shell, to which it has a very great resemblance. I 

 have now before me a very large number of this small form, 

 also from Darjiling, given me to look through by Mr. G. 

 Nevill ; and on a closer examination the differences are well 

 marked. 



In a drawing made under the superintendence of Stoliczka 

 the animal of this small form of Plectopylis is represented as 

 of a pink colour. 



In form the shell resembles macromphalus ; but it may 

 be distinguished by possessing a hairy epidermis, which, 

 on microscopical examination, differs from pinacis in being 

 laterally barred with brown, whereas macrompkalus, in a large 

 series, is uniformly coloured — also by the more distinct charac- 

 ter of a ridge on the parietal side of the aperture, not present 

 in the Khasi shell at its most advanced stage of growth. In 

 most respects it is really a closer ally of pinacis from the 

 same locality. 



The second species is also supposed to have come from the 

 same part of the Himalayas. 



