BIVALVIA. 141 
Crenulated in the mature state. Not crenulated at any stage of growth. 
Astarte Basterotii. Astarte borealis. 
5  Burtini. > compressa. 
»,  crebricostata. »,  elliptica. 
5,  crebrilirata. ,  Forbesil. 
>>  incrassata. » parvula, 
»  Galeottil. 
>  mutabilis. 
»  obliquata. 
»  pygmea. 
sy) Omalii 
5,  Ssulcata. 
»  triangularis. 
The different formations to which these species belong will be found in my Com- 
pendium or General Table. 
Woopra picirariaA. Crag Moll., vol. u, p. 190, Tab. XVII, fig. 8 (as Astarte digitaria) ; 
Supplement, Tab. X, fig. 8 a. 
Localities. Coralline Crag passim. Red Crag, Walton, Bentley, and Butley (Be//). 
Middle Glacial, Hopton. 
Var. Hoptonensis, Supplement, Tab. X, fig. 8 4. 
Locality. Middle Glacial, Hopton. 
The small shell represented in ‘Supplement,’ Tab. X, fig. 8 4, is from the Middle 
Glacial sand of Hopton, and as it seems to differ materially from the Coralline and Red 
Crag specimens I think it deserving of a separate figure. This Middle Glacial shell is 
much less transverse than any of my specimens from either the Coralline’ or Red Crags, 
and the elliptical markings much more distant, being scarcely half so numerous as in the 
Cor. Crag specimens. I have found specimens of the same species at Walton Naze and 
they are of an intermediate form, with the elliptical lines more distant than those upon 
the Cor. Crag specimens, but not so much so as upon the Glacial one, while the form 
of all the Red Crag specimens is generally even more transverse than the Coralline 
Crag ones. 
I had another figure (‘ Supplement,’ Tab. X, fig. 8 a) made of the Cor. Crag shell 
in order to show the ornamentation on the posterior side of the shell, which is not 
distinctly shown in the figures in Tab. XVII, but the artist has not been fortunate in his 
representation. These are transverse to the sulcations and form ridges upon them. They 
1 Since the above was in type I have found in the Coralline Crag a specimen presenting the elliptical 
markings nearly as distinct as in the Hopton specimen. This, however, is the only example presenting that 
feature which I have met with among the very numerous Coralline Crag specimens of this species that have 
passed through my hands. 
