98 
TURBO. 
A. Pillar margin of the aperture dilated, imper- 
forate. (Plate XIX. Fig. 4.) 
B. Solid, imperforate. (Fig. 5.) 
C. Solid, perforate. (Fig. 6.) 
D. Cancellate. (Fig. 7.) 
E. Tapering. (Fig. 8.) 
Shell univalve, spiral. Aperture coarctate, 
round, entire. 
The shells of the genera Turbo and Trochus 
are extremely similar, and are much intermixed in 
the Linnsean arrangement ; yet the round aperture 
of the one, and the angular form which charac- 
terizes the other, ought sufficiently to point out to 
which each belongs. The probability is, however, 
that the Turbines which have escaped from their 
proper genus, are fewer than the strangers which 
have been admitted into it. The rotundity of the 
mouth is a less indeterminate diagnosis than that 
of almost any other genus ; and even in these spe- 
cies in which it has an inclination to oval or ovate. 
