106 
PATELLA. 
A. Furnished with an internal lip or chamber. 
(Plate XXL Fig. 3.) (Fig. 4.) 
B. Margin angular, or irregularly toothed. 
(Fig. 5.) 
C. With a pointed, recurved apex. (Fig. 6.) 
D. Very entire, not pointed at the apex. 
(Fig- 7.) 
E. Having the apex perforated. (Fig. 8.) 
Shell univalve, conical, mostly without spire. 
The division C., consisting of shells with a re- 
curved apex, forms a natural link between this 
genus and the last described. The curvature of 
the apex approaches more or less to a regular 
spire, and in some species is precisely of the same 
description as that of a Haliotis ; but, then, the 
shell is not flat and ear-shaped, and therefore can- 
not belong to Haliotis, or to any existing genus 
but Patella, for there are none equally patulous 
with these two. The gradations in the scale of 
nature are in general so regular and yet so small, 
that it becomes no easy task to trace the sepa- 
