HELIX THELIDOMUS. 59 



more densely and conspicuously granulated and less variegated than 

 II. incerta. More important differences are in the more dilated 

 form (note the ratio of the two diameters), and in the greater devel- 

 opment of the peristome. The columella is nearly horizontal, and 

 bears a strong callus fold about the middle. 



Two variations deserve notice ; one, var. CASTRENSIS Pfr., repre- 

 sented on pi. 1, fig. 3, is nearly devoid of granules, more carinate 

 than the type, and conspicuously obliquely streaked ; the other, pi. 

 1, fig. 4, is very small and less granulate than the type. 



H. ASPERA Ferussac. PL 4, figs. 32-35. 



Imperforate, large, solid, globose-depressed, lusterless, white, or 

 more or less clouded with brown, especially toward the aperture, the 

 upper whorls generally with a few T zigzag brown markings ; entire 

 surface of the last two whorls densely coarsely granular; apex planu- 

 late, inner whorl white, smooth ; suture linear ; whorls 3, very rapid- 

 ly widening, the last transversely dilated ; body-whorl large, round- 

 ed, deeply, abruptly deflexed anteriorly ; aperture oblong, peristome 

 revolute, heavy, baso-columellar adnate to the base, broad, oblique, 

 flattened, the inner edge nearly straight and almost always bearing 

 a series of strong comb-like teeth ; parietal callus brown.. 



Alt. 35, diam. maj. 55, min. 40 mill. 



Jamaica. 



H.aspera FER., Hist, t. 44, f. 1-3 PFR. Conchyl. Cab., t. 62, f. 1, 

 2 RVE., f. 207. H. granosa WOOD, Ind. Test., suppl, t. 7, f. 45. 



A well-known form, distinct from the following in the granulation 

 of the surface and the teeth of the columella. 



H. COGNATA Ferussac. PL 4, figs. 38, 39. 



Imperforate, large, solid, globose-depressed, very similar in form, 

 size, and shape of whorls to H. aspera. The surface is clouded with 

 dark brown, is nearly smooth and somewhat shining ; whorls 3J, 

 very rapidly widening, the last deflected anteriorly ; aperture oblong, 

 livid within, the lip white, revolute ; columellar margin concave, its 

 inner edge simple or obsoletely toothed. 



Alt. 33 diam. maj. 53, min. 38 mill. 



Jamaica. 



H. cognata FER., Hist., t. 44, f. 4. PFR. Symb., iii, p. 72. PFR., 

 Conchyl Cab., t. 43, f. 5, 6. Eve. Conch Icon., f. 180. 



