STRATIGRAPHY OF CALIFORNIA COAST RANGES. 423 
slate at Slate’s Springs on the coast of Monterey county. This 
locality was revisited the past fall in company with Mr. Ander- 
son, and a collection made embracing five species of lamelli- 
branchs and a number of plants. The former though somewhat 
crushed were well enough preserved for generic determination. 
Unfortunately they proved to be very puzzling and threw but 
little light on the question at issue. They were submitted to 
Mr. T. W. Stanton for determination and the following descrip- 
tion is given by him: ‘The collection includes a large species 
of Lnoceramus, a large Homomya (?), Macrodon, Leda and Rhyn- 
chonella, none of which can now be referred to described species. 
The /noceramus seems to me the most important form in deter- 
mining the age, as it is confined to the Mesozoic, and a species 
of this size and type is probably not older than the Jurassic and 
might be Cretaceous. Jnoceramus quatsinoensis, Whiteaves, from 
the Aucella-bearing Cretaceous beds of Vancouver is a similar 
species. ‘Taking this in connection with the statements of your- 
self and Mr. Anderson concerning the field and stratigraphic 
relations of the beds, the most reasonable inference would seem 
to be Jurassic. The other fossils apparently do not conflict with 
TS ELekerences 
In the absence of confirmatory evidence the /noceramus from 
Alcatraz Island cannot be accepted as proof of the Cretaceous 
age of the strata there, and it is very probable that the horizon 
represented is the same or nearly the same as that of the Slate’s 
Springs beds. 
The recent discovery of radiolaria in the jasper of the 
Golden Gate series not only adds greatly to the interest of these 
rocks but also may aid in the solution of the age problem. 
Those found by Mr. Ransome and Professor Lawson, and sub- 
mitted to Mr. Hinde for examination, are, according to his 
description, forms similar to those occurring in the jasper of the 
Upper Jurassic and Lower Cretaceous of Europe. A part of the 
European beds containing the radiolaria are believed to belong 
to the upper Jurassic, while opinion is divided as to the exact 
horizon of the others. The specimens obtained by the writer 
