FISSURELLA. 9 
FISSURELLA. 
Shield-shaped, conically depressed, concave within ; 
vertex perforated ; destitute of a spire, and ob- 
long-ovate shape. 
F. nimposa. Ovate-oblong, convex, yellow- 
ish white, and adorned with purplish-brown rays, 
and many close-arranged longitudinal striz ; mar- 
gin crenulated ; perforation oblong, and contracted 
in the middle; greenish within. 13...1]. W. 
38. 99. 
F.Graca. Ovate-oblong, cancellated; sum- 
mit somewhat lateral; margin arcuated, and in- 
ternally strongly crenated, whitish, and sub-rayed 
with greenish; a dark horse-shoe mark almost 
surrounds the perforation (English specimens of 
this species are devoid of this latter character- 
iwc); inside white. 12 ...2. B.. W. 33. OF. 
F. noposa. Oval, convexly pyramidal, whit- 
ish, transversely annulated ; longitudinal ribs 
armed with great tubercles, which are cleft at 
the apex, and laterally compressed; perforation 
oblong, contracted in the middle like a key-hole, 
and surrounded internally with a white callus. 
fee WS8.: 9S: 
F. BARBADENSIS. Ovate-oblong, with un- 
equal longitudinal nodulous ribs, yellowish white, 
either rayed or concentrically spotted with red; 
perforation round and sub-central; margin toothed 
B2 
