144 



DESCRIPTION OF A NEW VARIETY OF ISOMERIA 

 SUBGASTANEA, PFR. 



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



Isomeria subcastanea v. kobeltiana, n. var. Figs, i, 2. 



Differs from the type in being larger and of lighter colour; the 

 whorls are less convex above, and the last is not inflated below, 

 behind the peristome; the base is less distinctly ribbed; the greater 

 portion of the lower surface and a narrow zone above the periphery, 

 are distinctly malleated in concentric rings, a character totally absent 

 in the type. The principal differences, however, lie in the peristome 

 and its teeth ; in the variety the peristome is strongly thickened and 

 broadly expanded, its basal margin is flattened, and its columellar 

 margin, which is almost straight, completely covers the umbilicus ; 

 these margins are subparallel and are united by a thick white callus 

 on the parietal wall. The outer tooth is not raised and there is only 

 one slight depression behind the peristome, corresponding to the 

 outer tooth ; to the left there is also a strong tooth sloping gently 

 towards the columellar margin. In the type, on the other hand, 

 the peristome is less thickened and expanded but more reflexed ; the 

 basal margin is deeply sinuous, the columellar margin convex at first, 

 then concave, and only partially reflected over the umbilicus ; there 

 is only one tooth which is raised on an eminence, with a corre- 

 sponding scrobiculation behind the peristome ; there is no second 

 tooth to the left, but there is a depression in its place behind the 

 peristome. A narrow milky band proceeds from the scrobiculation 

 below the periphery, and gradually loses itself. 



Measurements of the variety Iwheltiana : Diam. maj. 47, min. 41, 

 alt. 23 mm. 



Hah. — Ecuador. 



Isomeria subcastanea was originally described by Broderip as 



