86 HELIX-DENTELLARIA. 



H. Isabella FER. Prodr. 87 ; Hist t. 47, f. 2. PER. Conchy I. Cab. 

 t. 10, f. 1, 2?; Monogr. i, p. 307. DROUET, Moll. Guyane franc, p. 

 54. H. barbadensis "Guild." PER. Monogr. i, p. 310. (H.guildingi 

 PER. olim.) H. dentiens var. DESH. in Fer. Hist. p. 148. Dentel- 

 laria Isabella W. G. BINN. Ann. N. Y. Acad. Sci. iii, p. Ill, t. 9, f. 

 B. (dentition.) 



I have above expressed my opinion that this form is quite dis- 

 tinct from H. dentiens. See remarks under that species. The 

 smaller size of H. Isabella and its smooth, not granulated, parietal 

 callus will separate it form H. orbiculata. It is sometimes uni- 

 colored, yellowish, or with a single narrow dark fascia. 



H. ORBICULATA Fenissac. PI. 28, figs. 1-4. 



Imperforate, depressed semi-globose, solid, opaque, shining, light 

 yellowish brown or greenish brown, with two narrow chestnut fasciae; 

 obliquely striate ; spire low, dome-shaped, obtuse ; apical whorl 

 flat; sutures linear except the last half of the outer, which becomes 

 impressed. Whorls 5i, nearly flat, the last gently descending an- 

 teriorly, a little gibbous above behind the aperture ; aperture 

 oblique, oblong-lunar, transverse ; peristome expanded all around, 

 livid brownish, basal margin nearly straight, reflexed, broad, flat- 

 tened, adnate to the base only in the vicinity of the umbilicus, not 

 toothed within ; terminations of peristome joined by a bright callus ; 

 peristome and parietal callus minutely granulate under a lens. 



Alt. 16, diarn. 30 mill ; alt. 23, diam. 34 mill. 



Martinique; San Lucia ; Guiana; Cayenne. 



H. orbiculata FER. Hist. t. 47, f. 3, 4 ; Prodr. 86. PER. Monogr. 

 i, p. 265 ; Conchyl. Cab. p. 39, t. 70, f. 9, 10. RVE, f. 251. BLAND, 

 Ann. Lye. N. H. N. Y. vi, p. 152. TATE, Ann. and Mag. N. H. 

 1869, p. 356. Dentellaria orbiculata W. G. BINN. Ann. N. Y. Acad. 

 Sci. iii, p. 110, t. 16, f. W, and t. 9, f. A (jaw and dentition.) 



The largest species of Dentellaria. The principal variation is in 

 the degree of elevation of the spire. The bands are sometimes lack- 

 ing ; and I have seen specimens with four narrow bands all near the 

 periphery. The periphery is often subangular ; the base is rather 

 flattened, and slightly concave around the axis. Two specimens 

 before me measure alt. 16, diam. 33 mill; alt. 20, diam. 33 mill. 



H. BADIA Ferussac. PL 29, figs. 25-27, 29, 30. 



Imperforate, depressed, solid, opaque, somewhat shining, uniform 

 dark chestnut colored, delicately striate, under a lens densely gran- 



