62 HELIX THELIDOMUS. 



spiral impressed lines, the base smoother ; spire short, apex planu- 

 late, glossy, the suture impressed ; whorls 4, convex, rapidly increas- 

 ing, the last large, wide, transversely dilated, rather suddenly 

 and deeply deflexed anteriorly ; aperture very oblique, irregularly 

 quadrangular; peristome reflexed in every part, rather narrowly 

 above, the upper margin arcuate, baso-columellar margin substraight- 

 ened, flattened, with an obtuse, subdentiform prominence on its 

 inner edge, near the insertion. 



Alt. 27, diam. maj. 42, min. 33 mill. 



Province of Trindad, Cuba. 



H. scabrosa POEY, Memorias, etc., i, p. 421, t. 34, f. 1-5, I.e. ii, p. 

 57, 67, t. 6, f. 13. PFR., Novit. Conch., p. 181, t. 49, f. 10, 11, and 

 Monogr., v, p. 287. 



The coarse, irregular, anastomosing incremental wrinkles of the 

 upper surface separate this species from any of the preceding, and 

 the microscopic impressed spiral lines from forms otherwise some- 

 what similar. The sculpture is not very well shown in the figure. 



B. Surface not cut by spiral incised lines. 

 H. AURICOMA Ferussac. PL 3, figs. 26-30. 



Imperforate, globose, rather solid, rather opaque, straw-color or 

 yellowish russet, strongly obliquely striate above, the striae or costulae 

 somewhat unequal and irregular, but very rarely anastomosing, the 

 interstices between them smooth or rarely a little wrinkled trans- 

 versely, base much smoother ; spire low-conical, apex obtuse, smooth, 

 white, sutures impressed ; whorls 4, convex, the last wide, rounded, 

 subgibbous toward the aperture, where it is deeply deflected ; aper- 

 ture very oblique, irregularly subquadrate; peristome expanded, 

 heavy, thick ; columella oblique, straightened, forming an angle at 

 its junction with the outer lip, and flattened, its inner edge more or 

 less obviously two-lobed. Alt. 30, diam. maj. 40, min. 34 mill. 



Entire Island of Cuba. 



H. auricoma FEB., Hist., t. 46, f. 7-9. ORB., Moll. Cuba, i, p. 143, 

 t. 5, f. 4-7. PFR., in Conchy 1. Cab., p. 54, t. 7, f. 3, 4. REEVE, 

 Conch. Icon. f. 239. H. microstoma LAM., An. s. Vert, vi. p. 72. 

 H. bonplandii VALEN., in Homb., Zool., ii, p. 239, t. 56, f. 3. (not 

 of Lam.) 



A species quite variable in size, but moderately constant in sculp- 

 ture and in the form, which is orbicular, not much dilated trans- 

 versely. The difference between the major and minor diameters is 



