CRETACEOUS FOSSILS. 181 



0. Ashburnbrii, Gabb. 



(Mactra AsAburnerii, Gabb ; Pal. Cal., Vol. 1, p. 153, pi. 22, fig. 127.) 



Very characteristic of the Chico Group, and extending as high up as the Tejon 

 Group, being found at all of the typical localities of both of these, as well as of 

 the included Martinez Group. 



ASAPHIS, Modeer. 



A. MULTICOSTATA, tl. 8. 

 PI. 29, Pig. 70. 



Shell small, elongate subquadrate, inequilateral; beaks nearly 

 central; cardinal margin sloping towards both ends, concavely in 

 advance, couvexly behind; base broadly and regularly convex; 

 anterior end rounded ; posterior obsoletely and obliquely sub- 

 truncated, convex; a broad, rounded angle running from the beaks 

 to the posterior basal margin. Surface marked by about sixty 

 small radiating ribs with somewhat wider interspaces, and crossed 

 by a few lines of growth. Muscular scars large; pallial line un- 

 known ; an internal thickening runs obliquely downwards and 

 forwards from the beaks to the anterior muscular scar, formino; 

 a marked depression on the cast. 



Length, .68 inch ; width, .4 inch ; height of single valve, .1 inch. 



A single mould and an internal cast, from the Crooked Creek of the Des Chutes 

 River, Central Oregon, east of the Cascade Mountains ; associated with Trigonia 

 Evansana, Turrilites Oregonensis, and other species, characteristic of the Chico 

 Group. These specimens, beyond a doubt of the same age as the fossils near 

 Jacksonville and on the Siskiyou Mountains, in Southern Oregon, were obtained 

 by me in 1864, while in Eastern Oregon. The occurrence of the formation east 

 of the Cascade range, as proved by these fossils, was published in January, 1867, 

 by Professor Whitney, in the Proceedings of the California Academy of Natural 

 Sciences, Vol. 3, page 309. In July, 1867, Professor Blake announced the same 

 fact, as a new discovery, in the American JournaJ of Science, page 118. I merelv 

 call attention to the circumstance here, to forestall any discussion on the claim to 

 priority of discovery, that might otherwise arise in the future ; profiting by our 

 experience in similar cases in the past. 



