54 BOOK OF SPECIES. 
oblique; the callus red, sub-divided, partly co- 
vering the umbilicus; diam. 2. 
N. ALBUMEN. Sub-orbicular, convex, de- 
pressed, thickish, smooth, reddish fulvous, flat 
beneath, milky; spire very blunt, and oblique; 
the somewhat heart-shaped callus on the inner 
lip partly concealing the umbilicus; diam. 1%. 
Woo. 17- 
N. MAMMILLA. Oval-ventricose, flattish 
convex, thickish, brilliant white; spire rather 
prominent; the callus of the inner lip of the 
adult entirely covering the umbilicus; diam. 14. 
W. 35. 19. 
N. MELANosTOMA. Oval-convex, depressed, 
ventricose, thin, fulvous, whitish, with a broad 
