258 PALAEONTOLOGY OF CALIFORNIA. 



with certainty, and of Nautilus Texanus and Volutilithes Navar- 

 roensis, yet open to a donbt, it seems that there was not a continu 

 ous land barrier between the two basins. Three out of the four 

 species enumerated, are from the Texan fauna, and are not known 

 so far north as Nebraska, though beds of equivalent age are found 

 in that Territory. It is very probable that future explorations 

 in the yet unknown region between the Saskatchewan and the 

 Pacific, north of our boundaries, will develop a more or less con 

 tinuous series of Cretaceous deposits, showing a similar link on 

 the north. The presence of Ammonites complexus on Vancouver 

 Island, and in California, and the known existence of Cretaceous 

 beds in Eastern Oregon, and northwest of the great lakes, render 

 this hypothesis not improbable. 



I need sa} 7 but little about the age of this deposit. Dr. ROEMER, 

 in his admirable work, "Kreidebildungen von Texas," has dis 

 cussed the subject in so able a manner as to leave me nothing to 

 add. He considers it to be on, or near, the horizon of the Lower 

 Chalk; an opinion in which I fully concur. 



So far as I am aware, this is only the second locality of Cre 

 taceous rocks reported in the whole area of Mexico. In 1839, 

 GALEOTTI published a paper in the Bulletin of the Brussels 

 Academy, on some Jurassic fossils from Tehuacan, in the state of 

 Puebla, some of which, at least, seem to belong to the Cretaceous, 

 rather than to the Jurassic formation. 



AMMONITES, Brug. 

 A. PEDERNALIS, Yon Buch. 



PI. 35, Fig. 1, 1 a. 



(A. Pedernahs, Von Buch; Ueber Cerat., p. 81, pi. 6, fig. 8-10.) 



(Id., Koem ; Kreid. Tex., p. 34, pi. 1, fig. 3, a-c.) 



(Id., Con. ; Emory's Keport, pi. 15, fig. 1.) 



(Id., Gabb ; Synop. Cret., Philos. Proc. ; 1861, p. 14.) 



(A. pleurisepta, Con.; Emory's Report, p. 159, Pedernalis on plate.) 



A peculiar variety of thip species, differing both from the figures in Kreid. 



