HELIX HEMITROCHUS. 31 



The upper surface bears fine, regular costee. The species seems 

 distinct from others. The locality was unknown until Mr. Thomp- 

 son, of New Bedford, Mass., received it from a small key lying near 

 the North end of Eleuthera. 



* * * 

 H. GILVA Ferussac. PL 11, figs. 5-7. 



This species heads a series of forms distinct from all of the preced- 

 ing species, but very closely related to one another. In this series, 

 as in that of H. gallopavonis, etc., the species are founded upon 

 characters of but slight importance, while the variations in each of 

 them seem to leave no lacunae in the succession of forms. We find 

 that in Hemitrochus, as some one has neatly said of the distinctions 

 in another department of zoology, "size and form count for very 

 little, and coloration for nothing at all." I am content to point out 

 such differences as I can see between the forms, leaving each in- 

 dividual student to decide for himself their claims to specific rank. 



Narrowly umbilicate, depressed-globose, thin, shining, white or 

 tinged with yellowish or pinkish, encircled by numerous narrow 

 blackish and brown bands, several of them generally continuous, 

 the others interrupted ; surface coarsely striate ; spire low, rather 

 obtuse ; apex minute ; sutures moderately impressed ; whorls 4|, the 

 last wide, depressed, rounded at the periphery, rather deeply deflex- 

 ed anteriorly ; aperture oblique, broad oval-lunar, showing the bands 

 within ; peristome expanded, rather thin, slightly labiate with brown 

 within, margins converging ; columella broadly reflexed, partly con- 

 cealing the umbilicus, brown or purplish ; umbilicus narrow, show- 

 ing a slight spiral furrow within, when not too much covered. 



Alt. 10, diam. 15 mill. Jurisdiction of Trinidad, Cuba. 



H. ailva FEB., Hist. t. 21A, f. 1. and Prodr. 36. D'ORB., (in 

 part) Moll. Cuba, t. 8, f. 9-12. PFR., Conchy 1. Cab. p. 340, t. 60, f. 

 9-12 ; Monographia i, p. 335. ARANGO, Fauna Mai. Cub. p. 77- 

 H. corrugata PFR. Symb. i. p. 41. (H. pallida RANG, teste Arango) 

 -H. tephrites MORELET, Test, noviss. i, p. 8. PFR., Mongr. iii p. 

 80. 



The bands are sometimes coalesced into two continuous broad 

 zones, leaving a white peripheral girdle. The more prominent char- 

 acters are the depressed form, the bands, part of them continuous. 

 Var. TEPHRITES Morelet. PL 31, figs. 22, 23. 



Smaller, more globose and more sharply striate than the type, 



