APPENDIX. 
SCYMNUS, ۰ 
2. 8. OCCIDENTALIS, Agassiz, Pl. I, figs. 9—13.— The few species upon which Cuvier founded 
the genus Scymnus have been of late subdivided by Müller and Henle into two genera—Scym- 
nus proper, and Lemargus—all of which are only known among the living. It is another 
of the highly interesting 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 mouth as great a difference from the true 
Scymnus and Leemargus as the two latter present when compared with one another. At all 
events, these teeth belong to the genus Scymnus, as established by Cuvier, and constitute 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 thecrown. Moreover, the inclina- 
tion of the central point upon its basis gives these teeth a certain resemblance to those of 
Spinax 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 Lemargus, 
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 repre- 
sentative of the type has been found in the Pacific ocean. 
GALEOCERDO, Miller and Henle. 
3. 6. PRODUCTUS, Agassiz, Pl. I, fig. 1-6.—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 indication 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 G'aleocerdo adoncus from the Eocene of Europe, and 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 of the Old World, 
I would have been at a loss to distinguish them. » 
The California species differs chiefly from the European in having the anterior margin of the. 
tooth less arched, with much more minute crenulations, and the serratures on the basilar margin 
rather smaller. 
PRIONODON, Müller and Henle. 
4. P. ANTIQUUS, Agassiz, Pl. I, figs. 15, 16.— Thus far no fossil shark of the tribe of Carcharias 
has been known among the fossils; and, as shown in the Poissons Fossiles, all the species formerly 
referred to the genus Carcharias have been ascertained to belong to the genus Carcharodon. 
Few discoveries 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 thelr width as well as in the shape of their edge ; belonging evidently to 
the genus Prionodon of Müller and Henle. The larger and broader ones having the edges 
‘serrated especially near the base, while the narrow ones are smooth and sharp. These 
