36 
Oolite of Caen, and adds that they are the only ones he has met 
with. Of these two. one is a young tooth, the other one very 
much worn, and neither resembles our Corallian species at all 
closely. Under these circumstances, I cannot hut feel much 
hesitation in applying the name H. ohtmus to our species— 
especially when we consider how wide an interval there is 
between the Oolite of Caen and our own Coralline Oolite. 
A figure of the spine (PI. I., fig. 16) accompanies this report. 
The edges of the specimen are rounded, giving it a fiattened 
oval aspect in section. The ridges are flat and wavy, and less 
sharply marked than is usual in the genus. There is no serratim, 
on the posterior margin. 
H. M. PLATNAUEE. 
