

H. Doc. 129. 31 



which are only known among the living. It is another of the highly in- 

 teresting discoveries of Mr. Blake, to have brought home two teeth from 

 the tertiaries of California belonging to this remarkable type. I would 

 even not hesitate to consider them as indicating a distinct genus, were 

 the number of specimens sufficient to warrant the inference that the 

 teeth present, in every position of the mouth, as great a difference from 

 the Scymnus and Lrernargus as the two latter present when compared 

 with one another. At all events, the teeth belong to the genus 

 Scymnus, as established by Cuvier, and it constitutes a very distinct 

 species on account of the strong bend backwards of the main point of 

 the tooth, and the distinct and rather marked serration of the edges 

 of the crown. Moreover, the inclination of the central point upon its 

 basis gives these teeth a certain resemblance with those of Spinex and 

 Centrophorus, and still more with Galeocerdo. The connexion of the 

 teeth of the same row of the jaw with one another, was evidently the 

 same as in the Scymnus and Lsemargus, as is plainly shown by the 

 notch upon the inner surface of the root, and the articulating tubercle 

 at the base of the enamel in both sides. 



The discovery of a fossil Scymnus in the tertiaries of California is 

 particularly interesting in a geographical point of view, since thus 

 far no representative of the type has been found in the Pacific ocean. 



GALEOCERDO, Miiller and Henle. 



3. G. PRODUCTUS, Agass. Two species only of living Galeocerdo 

 have been known thus far one from the Indian ocean and one 

 from the Atlantic. The fossil species have been traced from the chalk 

 to the upper tertiaries. 



The Atlantic States have already yielded satisfactory indications of 

 the presence of this genus during the tertiary period, on the eastern 

 coast of America. Now we receive from the collection of Mr. Blake 

 a new addition to the range of this remarkable genus. The new 

 species he has discovered resembles so closely the Galeocerdo Adoncus 

 from the Eocene of Europe, especially common in- the Molasse of 

 Switzerland, that were there not several specimens in the collection 

 agreeing with one another in every respect, and unitedly differing 

 from those in the Old World, I would have been at a loss to distin- 

 guish them. The California species differ chiefly from the European 

 in having the anterior margin of the tooth less arched, with much 

 more minute crenulations, and the serraturcs on the basilar margin 

 rather smaller. 



PRIONODON, Miiller and Henle. 



4. p. AXTIQUUS, Agas. Thus far no fossil shark of the tribe of Car- 

 charias has been known among the fossils, and, as shown in the Pois- 

 son Fossiles, all the species formerly referred to the genus Carcharias 

 have been ascertained to belong to the genus Carcharodon. Few dis- 

 coveries in this field could, therefore, be of more interest than finding 

 among the tertiaries of Ocoya creek a number of teeth agreeing in the 

 deep notch upon the base of the root, but differing in their width as 

 well as in the shape of their edge ; belonging evidently to the genus 



