Geol.— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 73 



LAMELLIBRANCHIATA 



3. Inoceramus adunca, sp. nov. 



Plate IX, Figs. 188 and 189. 



Shell equivalve or nearly so, narrowly oval; margin elliptical; anterior side 

 short, rounded, sloping rapidly from the beaks; base forming a broad curve; 

 posterior side longer than high, meeting the basal margin in a rounded point; 

 beaks high, very prominent and full, forming a strongly curved hook; surface 

 having moderately strong concentric ridges, not regularly disposed. 



Length of shell 5.8 cm.; height 3.15 cm.; thickness of each valve 2.25 cm. 



This shell recalls by its strongly curved beaks some of 

 the species of the Colorado group of the Upper Missouri 

 section. 



Occurrence. — A single specimen of this shell was found 

 at the Forty-nine Mine, near Phoenix, Oregon, associated 

 with species of Schlcenhachia, Scaphttes, Lytoceras, and 

 Desmoceras. It apparently belongs to the horizon of the 

 Lower Chico. 



4. Inoceramus klamathensis, sp. nov. 

 Plate IX, Figs. 185 and 186. 



Shell small, not attaining a size much above that shown in the figures, in- 

 equivalve, the left valve being much more strongly arched, the right being 

 somewhat flattened, or compressed; left valve showing a tendency to form 

 an umbonal angle and depression at mature age; hinge line short, and form- 

 ing an angle of 60 degrees with the anterior margin. 



In the largest specimen found the length of the shell from the point of the 

 long, narrow beak to the extreme border is about 40 nim., width 25 mm.; 

 curvature of the left valve about 15 mm. 



Occurrence. — This species was found in the Lower Chico 

 beds of Willow Creek, Siskiyou County, California, and 

 at the Forty-nine Mine in Southern Oregon. 



5. Pholadomya anaana, sp. nov. 



Plate VII, Fig. 151. 



Shell gibbous, oval, rounded on the anterior and lower margins, narrowing 

 rapidly behind; beaks subcentral, but a little in advance of the middle, high 



