66 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Other, and both must be taken together to make up a really- 

 representative Lower Cretaceous fauna." Of their syn- 

 chrony he apparently has no doubt. 



In his summary of the deposits of San Luis Potosi, 

 Mexico (Stanton, 1895, p. 26), he recognizes therein 

 equivalents not only of the Knoxville, but apparently also 

 of the Upper Cretaceous, possibly of the Horsetown ; 

 while below these is the lower division of group No. 2, 

 which he refers to the Jurassic. It shows a general resem- 

 blance to the fauna of the Mariposa beds in the large num- 

 ber of species of Perisphinctes, and in the presence of 

 Olcostephanus, Belemnttes, and Aucella. 



The equivalents of the lowest portion of the Sacramento 

 section have not yet been clearly recognized. As to 

 whether the group which has been termed the Sub-Knox- 

 ville should really be classed with the Cretaceous or with 

 the Jurassic, there has been a difference of opinion. C. A. 

 White was convinced that but a single species of Aucella 

 was known from the Knoxville and from the Mariposa 

 beds; and the separation of these groups was not deter- 

 mined by a distinction of the species of this doubtful genus. 

 J. P. Smith (1895, p. 381) has expressed views strongly 

 favoring the Jurassic determination not only of the Sub- 

 Knoxville fauna with Aucella fiochi, but he also points 

 out the very close relationship between certain members of 

 the Knoxville fauna and the Volga stage of Russia. Quite 

 similarly, the lowest beds of the Queen Charlotte Islands 

 section, a portion of "Division C" of J. F. Whiteaves 

 (1876-84), has been compared to the same horizon of Russia. 

 The Knoxville horizon, as here restricted, has not been 

 shown to occur either upon the Queen Charlotte Islands 

 or upon the mainland of British Columbia. The relation- 

 ship between these beds and the Russian deposits appears 

 most strongly in some of the ammonites, which have not 

 been found-in any of the Californian beds. If this obser- 

 vation proves to be trustworthy, then the Sub-Knoxville of 

 the Sacramento basin is perhaps the equivalent of the low- 

 est member of the Queen Charlotte Islands group, or of 



