HELIX THELIDOMUS. 61 



Province of Trinidad, Cuba, at head-waters of the rivers Caballero 

 and San Juan. 



H. petitiana d'ORB., Moll Cuba, p. 144, t. 9, f. 1-3. (1853)-PrR., 

 Monogr., \, p. 263, and in Conchy I. Cab., t. 157, f. 1, 2. 



Allied to H. guanensis, but (typically) larger, and more depress- 

 ed. It is always smoother than that species, aperture is much more 

 oblique, the lip more broadly reflected, and the callus plate of the 

 columella more truncate ; although in this character H. petitiana is 

 somewhat variable. 



H. GUANENSIS Poey. PI. 3, figs. 21-23. 



Imperforate, large, depressed-globose, rather opaque, scarcely 

 shining, cuticle stronger than in H. petitiana, golden-brown, but 

 sometimes light enough to be called straw-colored ; upper surface 

 more or less strongly, regularly, obliquely striate, sometimes costulate, 

 sometimes nearly smooth, smoother beneath ; under a lens seen to be 

 densely marked with microscopic spiral impressed lines ; spire short, 

 apex planulate, inner whorl glossy, white ; sutures impressed ; whorls 

 4, convex, rapidly widening, the last wide, convex, anteriorly rather 

 deeply deflexed ; aperture quite oblique, truncate-oval ; peristome 

 reflexed, thickened, upper and outer margins arcuate, baso-columella 

 margin straighter, flattened, adnate to the base. 



Alt. 35, diam. maj. 55, min. 40 mill. ; alt. 35, diam. maj. 43, min. 

 36 mill. 



Guane, Cuba. 



H. guanensis POEY, Memorias Hist. Nat. Cuba, ii, p.35, pi. 4, f. 

 11-14. (1856-'58.) PFR., Novit. Conch., p. 180, t. 49, f. 1-3. 

 ARANGO, Faun. Mai. Cub., p. 70. 



This species is separated from H. auricoma and its allies by the 

 possession of microscopic spiral impressed lines lacking in those 

 species. It differs from H. petitiana in being more coarsely striate, 

 darker colored, and especially in the wider, less oblique aperture, its 

 peristome less broadly reflected. There is great variation in the 

 sculpture of oblique striae, but look for the diagnostic spiral lines. 



H. SCABROSA Poey. PL 4, figs. 40, 41. 



Imperforate, depressed-globose, solid, opaque, nearly lusterless, 

 light golden-brown, the upper surface rather coarsely costulate- 

 striate, the costulse irregular, anastomosing and bifurcating, them- 

 selves covered by a microscopic sculpture of oblique wrinkles and 



