University of California. 



[Vol. \i 



by Rust to indicate a horizon of the lower Gault, but Dr. Parona 

 thinks that the beds are much older. 



The most distinctive feature in the Californian radiolaria is the 

 number and variety of forms of the genus Dictyomitra present in it, 

 and it is not without significance that this genus is also abundantly 

 represented in the Jurassic and Cretaceous radiolarian jaspers and 

 cherts mentioned above. 



No other microscopic organisms besides radiolaria can be seen 

 in the Angel Island or in the Buri-buri beds. It is quite possible that 

 diatoms may have been intermingled with radiolaria in these depos- 

 its, but the fossilization, which has been sufficient to obliterate most 

 of the radiolarian structure, would completely destroy all traces of 

 the smaller and more delicate diatoms. 



Below are some further details respecting the forms which per- 

 mitted of partial identification. 



RADIOLARIA. 



Suborder, SpH/Ekoidea, Haeckel. 

 Genus, Cenosphajra, Ehrenberg. 

 To this genus belong the forms with circular or subcircular out- 

 lines, without spines. (Figs. I, 2, 3.) There is considerable varia- 

 tion in the size of different examples; they range from .055 mm. to 

 .3 mm. in diameter. The lattice structure is in almost all cases 

 destroyed; in one instance, however, the holes in the test are shown 

 in section. (Fig. 1.) These apparently spherical forms occur both at 

 Angel Island and Buri-buri Ridge ; they are more common in the 

 latter bed. 



Genus, Carposphsera, Hteckel. 

 Only a single example with an inner medullary shell has been 

 noticed. (Fig. 4.) The diameter of the test, .125 mm.; of the inner 

 shell, .045 mm. From Buri-buri Ridge. 



Suborder, Prunoidea, Haeckel. 

 Genus, Cenellipsis, Hceckel. 

 The tests are regularly oval in outline, with smooth surfaces. 

 (Figs. 5, 6, 7.) Their long diameters range from .1 to .22 mm., 

 the shorter from .08 to .185 mm. In one specimen (Fig. 5) the 

 thickness of the wall is .015 mm., but no perforations are shown; 



