138 CALIFOKNIA ACADEMY OF SCIENCES. 



specimen figured is from the lower San Pedro series at Deadmati Island, and is now 

 in the collection of Delos Arnold. 



Living. — Pnget Sound to Lower California; England (Carpenter). 



rieisiocene. — San Pedro (Arnold). 



Family XXV. KELLIELLID.E. 



Genus Aligena //. C. Leu. 



Shtll rounded, triangular, inflated; single small anterior tooth under the beaks, separated 

 by a gap from the surface of attachment, under the posterior dorsal margin, of an elongate internal 

 resilium carrying a lithodisma. 



Type, Aligena striata (Lea). 



70. Aligena cerritensis, sp. nov. 



Plate XIII, Fig. 3. 



Shell small, rounded, triangular, inflated, thin; inequilateral, the umbo being nearly terminal 

 posteriorly; anterior dorsal margin nearly straight; anterior e.xtremity quite sharply rounded and 

 produced furthest below middle; posterior extremity sloping off abruptly from umbo and rounded 

 near base; ventral margin arcuate; surface with faint concentric sculpture; umbones small, pointed, 

 anteriorly twisted, with a minute tooth below them on the cardinal margin; pallial line entire; muscle- 

 scars subequal. 



Dimensions. — Long. 85 mm.; alt. 8 mm.; diam. 5 mm. 



This species resemhles Acila casire7isis in outline. Specimens identified by 

 Dr. Dall, who pronounced it a new species. 



Two specimens from the upper San Pedro series of Los Cerritos, one of which 

 is the type, which is figured, and is now in the United States National Museum. 



Pleistocene. — San Pedro (Arnold). 



Siipcrfamily CARDIACEA. 



Family XXVL CARDIIDiE. 



Genus Cardium (Linnej Lamarck. 



Siiell variably sculptured, usually with predominantly radial ornamentation, usually closed 

 or ga])ing but sligluly, with no lunule or escutcheon ; pallial line rather distant from the margin of 

 the valves. 



Subgenus Trachycardium March. 



Shell rotund, closed, with the ribs imbricate or granulose; the channels also sometimes 

 granulose ; lelt cardinals anterior when interlocked. 



'Vy\)i.', Vardiinn isocardin. (Linin'). 



