450 TKOCKKDINGS OF THE ACADEMY OP" [1890. 



amply sufficient for relegating the inountaiu deposits of the region 

 under consideration to the Cretaceous formation ; and Gabb implies 

 as much in a prefatory I'emark contained in his report on a collec- 

 tion of fossils fnwn near Arivechi, State of Sonora.^ In this report 

 the author clearly establishes the existence of Cretaceous deposits in 

 the northern part of the Republic, and draws attention to the close 

 connection existing between the contained fossils and those from the 

 Cretaceous of Texas. Much more marked, on the other hand, is the 

 variation from the Californian fossils of approximately the same 

 horizon.'' 



Mr. Gabb records the following fossils from the deposits of Arive- 

 chi : 



Ammonites Pedernalis, Von Buch. — Species also occurring in the 

 Cretaceous of Texas. 

 Fusus Mexicanus, Gabb. 



Limatia Pedernalis, Roemer. — Also found in Texas. 

 Euspira tabulata, Gabb. 

 Chemnitzia zebra, Gabb. 

 C. Texana, Roemer. — Cretaceous of Texas. 

 Tylostoma mutabilis, Gabb. 

 Anchura ynonilifera, Gabb. 

 Cerithium Mexicanum, Gabb. 

 Tarritella seriatim-gramdata, Roemer. — Texas. 

 Angaria (Delphinnla) cingulata, Gabb. 

 Cinnlia redilabruvi, Gabb. 

 Pholadomya So)ioriensis, Gabb. 

 Tapes Hilgardi, Shuraai'd. — Cretaceous of Texas. 

 Cardium {Granocardium) subulosuvi, Gabb. 

 C. (Protocardium) granulifermn, Gabb. 

 Cardita ? alticosta, Gabb. 

 Pinna sp. indet. 



1 Geological Survey of California, Paleontology, II, p. 258. 



2 A preliminary notice of the Sonoran fossils was published in vol. Ill of the 

 Proceedings of the California Academy of Sciences, 1864, p. 153 The fossilifer- 

 ous rock, as described by M. Remond, lies about a league and a half east of Arivechi 

 in the Sahuaripa Valley, and consists of clay-slates, 400-500 ft. in thickness, rest- 

 ing upon barren sandstones, and underlying thick strata of compact bluish lime- 

 stone. " The strata dip to the south-east with an inclination of from thirty to fifty 

 degrees, and form the first range of foot-hills of the Sierra Madre." 



