184 TRANS. OF THE ACAD. OF SCIENCE. 
towards the miele which is ma and curved beneath the del- 
tidium ; area, very narrow or obsolete 
Length, 0.94; breadth, 1. 25; thickness, 0.62; height of area, 
0.28; width of area and "length of cardinal line e, 0.64, 
Our shell differs from the O. Fey iat in being less 
more Genidienl radiating lines regular and pte as us from 
argins. 
ornée de stries ‘éliées, flif ormes, deux ou trois fois plus étroites 
que les intervalles qui les separent,” musket t of 
our shell; and, besides, ours has concentric s 
Major Hawn’ s collection from the haves Peraug Rocks, 
in the wih han the Cotton-wood, K. T., where it is associa-— 
ted with niscus dubius, yee Halli, and Monotis 
vari 
ACEPHALA. 
“Shel beoiiewdcs kehaubicutae. obiaee, with a deep, rounded 
= etween Saneabripge the adjacent sides; cardinal bor 
