SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 131 



in portions of the same tree, which may be granular and friable ; 

 Others solid and amorphous throughout, or changing in the 

 space of a few inches to a fibrous, easily separable mass of 

 silicious, silky threads, or to carbonaceous matter but little 

 changed from its original ligneous character. 



Around the bay of San Francisco, and at other localities, 

 trunks of redwood trees, which have undergone but little change, 

 are often encountered in drilling for artesian wells ; on the east 

 side of the bay these fossil trees are usually found at a depth 

 of about two hundred feet. 



California during the earlier geological ages not having 

 emerged from its ocean bed, had a very scanty flora. During the 

 Cretaceous Age, some fragments of the trees which grew on the 

 limited area of land were floated out into the cretaceous sea, be- 

 came silicified, and were buried in the silt of the ocean bed, and 

 may be found occasionally in the cretaceous rocks which have 

 been exposed in different localities in the State. Specimens of 

 this character, which before being silicified, had been bored by the 

 Pholads, or "Boring Mollusks," have been found by the writer 

 in the ammonite beds of Shasta County, and other fossilized frag- 

 ments in Alameda County, in which locality the fossil wood 

 formed the nuclei of concretions of indurated clay and sand. 



In the later geological periods, after the emergence of the 

 land, terrestial plants grew upon the entire area of dry land, and 

 their fossil remains have been imbedded in the strata of the 

 rocks in such an excellent state of preservation that the laminae 

 may be separated, showing the leaves and other portions of the 

 trees and plants preserved between the laminae, like fossil photo- 

 graphs of the vegetable hfe of bygone ages. 



The following is a list of the known fossil plants of Cali- 

 fornia, except such as have not yet been determined. 



Some of the species submitted to the eminent paleobotanists, 

 the late Professor Leo Lesquereux, and Dr. J. S. Newberry, were 

 not published during their lifetime, and will probably be deter- 

 mined or described by others. 



CRYPTOGAMAE. 



ALGAE. 



Fucoides are found in the Cretaceous rocks, and in a great many 

 localities in the Tertiary ; in Alameda County specimens 

 were brought to me as "Fossil Snakes," or "Fossil Eels." 

 which proved to be the stems of fossil sea weeds. 



EOUISETACEAE. 



Bquisetiim ( Horsetail ) . 

 Bquiscfwn sp. — Corral Hollow, San Joaquin County; Miocene. 

 Bquisetum^ undeterminable species, related to E. Wyomingense 

 Lesq. Contra Costa County; Miocene. 



