144 CALIFOKNIA ACADEMY OF SCIENCES. 



lunule not excavated, but bounded by an impressed line; hinjjje not strong; two small cardinal teeth; 

 ligamental area excavated, internal. 



Dimensions. — Long. 38 mm.; alt. 30 mm.; diam. 10 mm.; length of lunule 12 mm. 



This species is distinguisliiible from C. sahdlaphana Carpenter by its promi- 

 nent impre-sseJ liinule-bounding line, ronnded pallial sinus, and by its coloration in 

 the living specimens. 



Rare in upper San Pedro series at Deadmau Island. Abundant at Twenty- 

 sixth Street, San Diego. 



Living. — Monterey to Catalina Island (Cooper): San Pedro (Williamson). 



Pleistocene. — San Pedro (Arnold): San Diego (Coo]ier; Arnold). 



Pliocene. — San Diego well (Cooper). 



79. Callista subdiaphana Carpenter. 



Plate XIII, Fig. 4. 



Clevie7ilia subdiaphana Cpr., Brit. Assn. Rept. 1863, p. 640; Proc. Phil. Acad. Sci., 1865, p. 56. 

 Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 235. Dall, Proc. U. S. Nat. Mus., 

 Vol. XIV, 1891, p. 185, PI. VII, figs. 5 and 6. 



Shell of medium size, oval, transverse, inequilateral, ventricose, rather thin; beaks small, 

 incurved; anterior extremity quite sharply angulated about middle of shell; posterior extremity much 

 longer and wider than anterior and very evenly rounded, projecting furthest a little below the 

 middle; ventral margin evenly arcuate; surface sculptured by numerous fine, regular, concentric, 

 incremental lines; neither lunule nor escutcheon, but a faint lunular circumscribing line in front of 

 umbo; three prominent, sharp, cardinal teeth in each valve, the anterior one being narrower and 

 longer than the other two; external ligamental groove long, narrow; pallial sinus cuneiform, rather deep. 



Dimensions. — Long. 43.5 mm.; alt. 34 mm.; diam. 26 mm.; umbo to anterior extremity 10 

 mm.; to posterior extremity 33.5 mm. 



This sjiecies is very close to Conrad's Dioue anr/usfiformis from the Astoria 

 Miocene, the external characteristics of both being almost identical. Specimens 

 identified by Dr. Dall. 



Rather common in the Pliocene of Deadman Island and Timm's Point. ' 

 Cooper's " Quarternary " at San Pedro includes the Pliocene, and his specimens 

 from San Pedro were probably from the Pliocene. The writer has never found 

 Callista subdiaphana in the Pleistocene of San Pedro or vicinity. The specimen 

 figured is from the Pliocene of Deadman Island, and is now in the collection of 

 Delos Arnold. 



Living. — South Alaska Coast to San Francisco (Dall). 



Pleistocene. — San Pedro to San Diego (Cooper). 



Pliocene. — San Diego well (Cooper): San Pedro (Arnold). 



80. Callista subdiaphana Carpenter, pedroana, var. nov. 



Plate XIII, Fio. 2. 



Shell of medium size, subelliptical, transverse, inequilateral, ventricose, rather thin; beaks 

 small, incurved; anterior extremity evenly rounded, short; posterior extremity faintly biangular, 



