OF COXCHOLOaY. 209 



The principal points of difference between this shell and H. 

 acutedentata are in the mouth. The teeth are but three in 

 number; one on the inner lip, similar to that of acutedentata, 

 but more twisted, narrower and truncated more obliquely be- 

 low ; the second tooth is a mere tubercle on the inner margin 

 of the outer lip; it is sometimes slightly prolonged, and 

 with the apex pointing outwards ; the last is a large and very 

 oblique fold on the basal part of the mouth; this latter cha- 

 racter is the most obvious one. There are no traces of the 

 internal oblique ribs in the upper part of the mouth, so cha- 

 racteristic of both H. loisa and H. acutedentata. The umbilicus 

 and lower aspect of the shell are very nearly identical with 

 the above quoted species. 



H. {Polygyra) anilis, Gabb.— t. 19, f. 1—4. 



Description. — H. testa orbiculata; superne spira depressa 

 infra minute umbilicata; anfractibus 4 — 4|; anfr. ult. ad aper 

 turam descendens, vix constricto ; umbilico angusto, profundo 

 apertura obliqua; labio unidentato; labro marginato, edentato, 

 reflexo. 



Locality. — With the preceding. 



My Cabinet. 



Shell a little more convex than the preceding, spire nearly 

 flat; whorls rounded, most prominent a little above the middle; 

 under surface showing about 1| volutions; umbilicus minute, 

 but distinctly perforate; suture impressed; surface polished 

 and microscopically striate; last whorl slightly descending 

 near the aperture, and a little constricted behind the lip; 

 aperture oblique, outer lip a little thickened and reflected, 

 ends connected on the inner side by a slight callus, which 

 bears a triangular pyramidal tooth, V shaped on its anterior 

 face. Greatest diameter "55 inch ; height '23 inch. 



