1913] Jordan-Beal: Supplementary Notes on Fossil Sharks 251 



shark's teeth. There is no doubt that Leriche is quite right in 

 referring all of these to one species, plana being the upper 

 lateral teeth, tumula the lower, and smithii the long and flexuous 

 front teeth. Similar differences are shown in the dentition of 

 the existing species, Isuropsis glauca. 



In this genus there are never serrations on the edge of the 

 teeth and never denticles at base. 



Some of these teeth are two and one-half inches in height, this 

 indicating a shark of sixty feet more or less in length. 



Leriche further identifies this species with Isurus hastalis 

 (Agassiz) of Europe, which view is very likely correct. Dr. 

 Priem refers similar teeth from the Miocene of Patagonia to 

 Isurus hastalis and Woodward records the same species from 

 Argentina. 



Another tooth referable to Isurus hastalis was obtained from 

 the lower Miocene at Stanford University, near the base of the 

 intruding basalt columns. Another was found by Mr. Harold 

 Hannibal in the Arago formation (Eocene) near Cape Gregory, 

 Oregon. Still another was obtained by Mr. Hannibal from the 

 Miocene of the east shore of Coos Bay, Oregon. This is quite 

 typical of the lateral upper teeth of Isurus hastalis. 



A large vertebra, nearly two inches in diameter, probably 

 belonging to Isurus hastalis was also found by Mr. Hannibal. 



15. Isurus desori (Agassiz). 



Chico formation, upper Cretaceous. 

 A single tooth, doubtfully identified with this species of the 

 European Cretaceous. 



Genus Carcharodon Smith 



16. Carcharodon megalodon Charlesworth. 



(Carcharodon branneri Jordan) 

 This giant shark's tooth named Carharodon branneri is dis- 

 tinguished from the equally large Carcharodon megalodon of the 

 Miocene of regions about the Atlantic Ocean, by the smaller 

 number of serrations on the large teeth. Of these we count 80 

 to 100 on each side in the specimens from California called 



