274 Scientific Intelligence. 
instance of a fossil species of the type of Carcharias of the genus Pri- 
onodon, which it will be possible, under all circumstances, to nding 
from Sphyrna by the difference in the shape and serrature 
in i reaper and lower jaw. The species may be Sciccant Prionodon 
My pepe denticulatus, from Maestricht, may, however, belong 
to this genus. The tooth of this species being rather erect, while in 
aan the crown of the tooth is bent backwards, and its posterior 
margin is deeply notched. In Prionodon antiquus, as well as in G. 
denticulatus, the crown is but slightly inclined backwards, and though 
it tapers rapidly to a conical point, that ‘ated does not stand so dis- 
tinctly out from its base as in true Galeocer 
(5.) Hemipristis Heteropleurus, Agas. nto nus s Hemipristis was 
established by me from fossil teeth of the middle t pact of Europ 
Dr. ibbes has since indicated their existence among the ae 
ries of the ane shores of America, and now we owe to Mr. Blake 
the Serivery of a tooth of this genus in the deposits of Ocoya creek, 
Califo 
I coi already remarked how difficult it is to perceive the diferente 
compare ed ah that of the anterior margin of the tooth. ve this may 
be found to be a constant character, i? would introduce the westerD spe- 
cies pileorepaess. under the name of H. heteropleurus, or until the 
discovery of more specimens decides whether this difference in the 
serrature of the margin of the inner sides of the teeth is constant oF not. 
; —Of all the types of sharks’ teeth 
that of Carcharodon, next to Lamna and Oxy rhina, is the most numer- 
‘an in the tertiary deposits, though there is only one living species 
a. Blake has brought a finely preserved specimen of a medium 
species of this one ies California, Rather smaller than Car- 
stidens, ooth has the same form as in that speciess 
only there are no. prone ie oo upon the sides of the base. Consid- 
idens, and to this shaabeier the name rectus is intended to allude. 
Pomona sees of this genus have been eiptoia by Dr. 
res a 
che sp species. The surface is flat and the tooth straight, as in C. angus” 
i 
i ‘in the sisi of the Atlantic s 
