306 Mr. W. T. Blanford on the Animal of Diploramatiiia. 



that the latter genus belongs to the Cyclostomacea, as was at first 

 inferred by my brother from the form of the aperture and the 

 sculpture, and that its nearest ally appears to be Diplommatina, 



Plectostoma DeCrespignii closely resembles the two Indian 

 species of Opisthostoma in the mode of flexure of the very re- 

 markable last whorl, in the form of the aperture, and in the 

 texture of the shell. There is a slight constriction at the spot 

 where the last whorl is first deflected, though this is less marked 

 than in Opisthostoma. The sculpture, though coarser, is smaller 

 in character. The most important distinction is in the form of 

 the spire, which is conical in Plectostoma] and the apical whorls 

 are not excentric to the axis of the lower whorls as they are in 

 the ovate spire of Opisthostoma. I scarcely think, however, that 

 these distinctions will be regarded by any conchologist as 

 generic ; at the most they are subgeneric. 



As I have but two specimens of the Labuan shell, I do not 

 like to sacrifice one for the purpose of searching for the opercu- 

 lum, especially as the search amongst these minute shells of the 

 Diplommatina group, in consequence of the small size and ex- 

 treme tenuity of the operculum, is by no means always success- 

 ful. I had to break open three or four specimens of Opistho- 

 stoma Fairbankii before I could obtain a glimpse of the oper- 

 culum, and then I failed in isolating it. If any one more 

 fortunate than I am, in the possession of specimens of Plecto- 

 stoma, will carefully break back the last whorl to the point where 

 it is deflected, or a little beyond, he will, I doubt not, find an 

 operculum ; and it will probably be horny, thin, and obscurely 

 spiral, with rather few whorls, as is usually the case with Diplom- 

 matina and its allies. 



2. On the Animal 0/ Diplommatina. 



I have more than once, within the last few years, called at- 

 tention to the circumstance that, in the two supplements to 

 Dr. Pfeiff'er^s admirable monograph of the living operculated 

 land- shells, the position assigned to the genus Diplommatina, 

 close to Acicula, and in a suborder distinguished 

 by the position of the eyes above the base of the 

 tentacles, is not in accordance with the structure 

 of the animal. For some years past I have not 

 had an opportunity of reexamining the animal 

 of any typical species of the genus. I am in- 

 debted to Captain Godwin-Austen for the ac- 

 companying outline sketch of the animal of a 

 species of Diplommatina inhabiting the Western «,' Slfof the^perture 

 Himalayas near Masiiri, and apparently a variety °^^^^ ^^^^' 

 of D. pullula, Benson, which was first found by myself near 



