HELIX-ISOMERIA. 141 



A species which can be compared with H. aloaganaJouss,., contimia 

 Pfr., and subelliplica Mouss. It is somewhat smaller than aloagana, 

 is not dilated transversely or oblong as that species is (compare the 

 lesser and greater diameters of the two forms), does not have so 

 gradual nor so great a deflexion of the body-whorl at the aperture, 

 is more broadly umbilicated with less dilated columellar lip, and 

 finally, has a small oblique denticle upon the parietal wall, which is 

 lacking in Jousseaume's species. The two specimens figured differ 

 slightly in elevation of the spire ; the depressed one is more strongly 

 costulate-striate above than the other shell, and darker colored. H. 

 subelliptica Mouss. is smaller, with more rounded periphery and 

 decidedly differently shaped and smaller aperture. 



H. FORDIANA Pilsbry. PL 62, figs. 18, 19, 20, 21. 



Almost covered umbilicate, globose depressed, solid and strong 

 but rather thin, opaque, of a rich chestnut color. The surface is 

 shining, obliquely striate, tinder a lens seen to be densely, minutely 

 granulate. The spire is very low, regularly convex, about as convex 

 as the base; the two apical whorls are a little lighter colored, and 

 quite convex ; the following whorls are almost flat, separated by 

 sutures scarcely at all impressed. There are about 4i whorls ; the 

 inner ones widen slowly ; the penultimate becomes rapidly very wide, 

 its last half being as wide as the adjacent arc of tne last whorl ; the 

 body-whorl is somewhat oblong or " transversely dilated," seen from 

 above ; it is angled at the periphery, convex beneath, becoming 

 more convex on its last third, and as it approaches the aperture it is 

 very abruptly and very deeply deflexed, deeply constricted behind the 

 peristome. The aperture is subhorizontal elliptical-truncate in out- 

 line, and is whitish livid inside ; the peristome is broadly expanded, 

 subreflexed, very little thickened, its face convex, not flattened, and 

 white or nearly so; the superior border of the lip is convex, wide, 

 stands out from the body-whorl where it joins it, and its plane is 

 more horizontal than the lower lip ; it is arcuate, passing in a 

 regular curve into the outer lip, which bears a small rather acute, 

 slightly compressed denticle on its inner edge, below the position of 

 the periphery-termination ; the basal lip is straightened (curving 

 into the outer lip), and bears in'the middle an obtuse node or tubercle 

 projecting upward ; the columellar insertion is dilated, almost closing 



