52 CONTRIBUTIONS 
Observations. A single valve of this interesting species 
has come into my possession. It is the left one. Its beau- 
tiful form eminently distinguishes it. The exterior portion 
of the valve is not perfect, and characters not observed on 
this specimen may be, perhaps, found on perfect ones. 
E. Bucklandit. Plate 1. Fig. 21. 
Description. Shell subtriangular, somewhat inflated, 
inequilateral, polished, obtusely angular before and at 
top; substance of the shell rather thin; posterior and an- 
terior slopes somewhat flattened; beaks somewhat ele- 
vated, pointed, incurved ; cavity of the shell not very deep ; 
inferior portion of the margin finely crenulate. 
Diam; a=. Length .7, Breadth 1, inch. 
Observations. Like the last described, a single valve 
of this beautiful species only has been found. It was 
taken out of a mass in about a dozen pieces and recon- 
structed. It resembles the triangulata in many of its cha- 
racters, but is more transverse, and is neither flat nor gib- 
bous on the exterior. In outline, it has some resemblance 
to a Donaz. 
In dedicating this species to the distinguished author of 
the “ Reliquiz Diluviane,” I will take the opportunity to 
make my acknowledgements for the pleasure and advan- 
tages derived from his various writings. Few geologists 
of Europe have, with the same success, cultivated the 
