Geol.-Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 



37 



It is not claimed that the Upper and Lower divisions of 

 the Chico are entirely distinct, but only that there is a 

 sufficient difference between them to warrant their dis- 

 crimination. 



In widely separated localities both portions of the Chico 

 seem to be represented together, though perhaps with more 

 careful study the deposits might be found separable. In 

 the vicinity of the Bay of San Francisco, four localities 

 may be mentioned which will be found interesting. The 

 connections between them are not known, except that they 

 are not distant from each other geographically. It will be 

 noticed that in two of these lists, Martinez and Pacheco 

 Pass, the species are prevailingly those of the Upper Chico, 

 though at Martinez a species of Trigonia occurs which has 

 been supposed peculiar to the Lower Chico. In the list 

 from Curry's, south of Mount Diablo, the species of the 

 Upper and Lower horizons appear to be about equally 

 mingled. A little farther south, in the Livermore Valley, 

 Alameda County, fossils occur that are certainly below the 

 Upper Chico, if not below the Lower; but this will be dis- 

 cussed later on. 



Pacheco Pass. 



Baculjtes chico'ensis Trask 

 Gyrodes conradiana Gabb 

 Lhna appressa Gabb 

 Lutraria truncata Gabb 



Meekia sella Gabb 

 Perissolax brevirostris Gabb 

 Pharella alta Gabb 

 Tellina matthewsoni Gabb 



Benicia, 



ActcBoniyia californica Gabb 

 Chione varians Gabb 

 Cucullcea truncata Gabb 

 Desmoceras jugalis Gabb 

 Eriphyla tunbo?iata Gabb 

 Fulgiiraria gabbi White 

 Globiconcha rei)iondi Gabb 

 Inoceranius whitneyi Gabb 

 Lytoceras batesi Trask 

 Mactra ashburneri Gabb 



C4) 



Margaritella globosa Gabb 



Meekia sella Gabb 



PachydiscHS newberryantis Meek 



{Ammonites fraternus Gabb) 

 Pectuncidus veatchi Gabb 

 Pharella alta Gabb 

 Trigonia evansana Meek 

 Trigonia leana Gabb 

 Turrit ella sp. 



November 12, 1902. 



