GREEN HELMET-SHELL. 
The Cassides, or Helmets, compose the 
fourteenth family of Dacosta's Univalves. *' I 
define it,*' says he, " Shells semi-globose, the- 
back being very convex or round, the un- 
der or mouth part flat. They have nearly 
flat, or at most very sholt, clavicles or tur- 
bans. The mouth is ions^, rather narrow, 
£ind ends at the top in, a gutter, which turns 
very large, strong, and wry on tiie hack ; the 
Hp ■ is always strongly and thickly toothed, 
and rises into a high and thick border or ledge, 
on the upper part or back ; and the pillar is 
most generally strongly toothed, ^ ridged, or set 
vviih small bumps or asperities. 
*' Some systematical authors have agreed 
with me, in making a distindl or particular 
faiiiily of tiiese shells, and call them Cassides: 
sach are Rumphius, Meuschen, and Gual- 
tieri. 
" Linnaeus ranks them as Buccina ; Argen- 
ville, and Davila, as Murices ; and, lastly. 
Lister, among his Buccina, by the name 
of Bellied or Swelled Whelks with a wry 
moyth. 
This • 
