BIVALVIA. 123 
This shell I have placed in the genus Zasea, as it corresponds in its dentition with 
Lasea rubra, and it has not the peculiar ornament of Zepton upon the exterior, but is 
covered with concentric striz or fine lines of growth. Mr. Jeffreys describes the recent 
shell as being “marked with longitudinal radiating lines” (‘ Brit. Conch.,’ vol. ui, 
p- 203) ; these are not visible in my fossil, but my specimens are rare. 
Lasaa interMEDIA, S. Wood. . Supplement, Tab. X, fig. 22. 
Locahties. Chillesford Bed, Aldeby. Middle Glacial, Hopton. 
The specimen figured was sent to me by Messrs. Crowfoot and Dowson, who found 
it with some others at Aldeby, anda single perfect specimen of the same species has 
been found by my son in the Hopton Sand. 
It resembles Lasea pumila of the Cor. Crag in size and outline, but it is much 
flatter or more compressed, and it differs essentially in its dentition. Our present shell 
is transversely ovate, very inequilateral, compressed, and with a smooth exterior; the 
right valve has a rudimentary cardinal tooth and a very elongated lateral tooth on the 
longer or pedal side, with a small one on the other nearly at right angles; the left valve 
has corresponding denticles, but not so prominent. 
At first I thought the present shell might be referred to 1. Dawsoni, ‘ Brit. Conch.,’ 
vol. 1, p. 178, but Mr. Jeffreys, who examined the Aldeby specimens, said “ this little 
bivalve is, I consider, the younger state of your Kellia pumila. Montacuta Dawsoni differs 
from it in being flatter and having no cardinal tooth, the lateral teeth being very much 
shorter and stronger.” The denticles of my shell are much longer than in either pumila or 
Dawsoni ; and 1 have, therefore, for the present, kept them distinct. My shell is by 
no means thin, and the anterior muscle-mark is large and deeply impressed, from which 
I think it is fnll grown. 
Bornia ovauis, S. Wood. Supplement, Tab. IX, figs. 3 a, 4. 
Locality. Cor. Crag, Sutton. 
Length, ths of an inch. 
Two specimens, both unfortunately of the same value, have lately been found by 
myself, and I am unable satisfactorily to refer them to a known species. My shell has 
two short but prominent diverging teeth, one on each side of the depression for the 
cartilaginous connector. There is an indentation in the umbo which much resembles 
that present in some species of Cocklodesma, through which the cartilage protrudes. 
This opening may have been made in a similar mamner, or it may be accidental. 
I have, from these imperfect materials, declined giving a diagnosis. 
17 
