The whole of these are Crelaeeons, unless, indeed, some of the membei's; 

 of the Shasta (i roup sliould prove to be of Upper Tithoiiie ao-e, which 

 is by no means iin])robabh'. 



Queen Clmilotte I^Uuids. 



Ammonites Timothcanus, Mayor 



Inoceramus coiicentiims, Parkinson 



Ammonites Brewerii, Gabb 



" Stoliczkamis, Gabb 



Aucella Piot-hii, Gabb (?= A. j\Ios(HU'nsis) . 

 Unio Hubbardi, Gabb 



Oriuinal Localities and Horizons. 



Gault of Switzerland. 



Gault of England. 



Sha.sta Group of California. 



Chico Group of Yaneouver Island. (Pro 

 babl_v an error.) 



The remainder belong, in manjr cases, to genera which originated in 

 the earlier part of the ^lesozoic age, and which are not yet extinct. 



Mr. G-abb has divided the Cretaceous rocks of the west coast oi' 

 America into the Sliasta, Chico, Martinez and Tejon Groups, but the 

 Martinez is now regarded as only a subdivision of the Chico flroup. 

 The "Shasta Group" is the oldest known member of the formation, 

 the name being originalh" suggested for a series of beds which the same 

 author believes to be the "equivalent, or at least the nearest repre- 

 sentative of the Neocomian.''* Ilfext in order comes the " Chico Cxroup.'' 

 an accumulation of sediments of immense thickness, ■' which includes all 

 of the known Ci'etaceous of Oregon, and of the extreme northern 

 portion of California," f also the Coal-bearing forn\ation of Vancouvei' 

 Ishind. According to Dana.'| the so-called '• Martinez Group " of Mount 

 Diablo, forms its uppermost subdivision. Lastly, the newest member of 

 all is the " Tejon Gi'oup," which is supposed to correspond to the Ma- 

 estricht beds of Europe, but which has not yet been recognized outside 

 of California. Nearly the whole mass of the Cretaceous formation of the 

 Pacific slopes is made up of the Shasta and Chico Groups, and Mr. 

 Eichardson estimates the thickness of the Vancouver Island deposits, 

 which are believed to belong to the latter of these two divisions, at 5,000 

 feet. 



* " Palffiontolog^- of California," Vol. II. Foot note to jiag-e 1'29. 



+ Idem. Preface, page xiv. 



{ "Manual of Geology." Second Edition, Page 457. 



