113 
GRYPHAA dilatata. 
TAB. CXLIX.---Fig. 1. 
Spre. Cuar. Orbicular, obscurely lobed; upper 
valve flat, lower valve hemispherical. 
Var. 6 distinctly lobed, Fig. 2. 
Snort as the beak of this is, it curves enough in most 
specimens to mark the Genus, besides this, the regular 
concavity of the lower valve and its lobed form are suffi- 
ciently characteristic ; the back of the flat valve in old 
specimens is straight and occupied by the hinge pit, 
which is not curved, and consequently diverges from the 
curved pit in the other valve; the lateral lobe varies, in 
some specimens it is very distinctly defined, in others 
obscure; but it may always be traced; the var. 6 has the 
lobe very strong and produced in both yalves. 
This, and the varieties into which it sports, are not 
rare, itis, therefore, necessary, if possible, to distinguish 
its characters as aspecies. The hinge, at first sight, and 
in a single specimen would appear to be nearly sufficient 
to generalize it, and is certainly of much use, although 
many varieties of different species of oysters have some 
approach to the characters peculiar to Gryphites, such 
as the curved beak and the lobe or sulcus: the great 
breadth and uniform concavity of the deep valve with the 
gaping hinge appear to be the essential characters. 
The upper specimen and some larger varieties, mea~ 
suring eight inches and ahalf diameter, I have had long 
since from Suffolk, by favour of Dr. Sutton. An odd 
variety, very broadly aggregated, with the side lamine 
more extravagant than the one figured, was brought me 
from Pakefield. I have one with many Vermicule and 
