lo8 ( Al.lluliMA .UAUKMV dl' Sl'lKNOES. 



specimen lii^iiied is from tlio lower San l\'dro scricsi al Deatliuan lalaiid, ami is now 

 in till- collection of Delos Arnold. 



Liviinj. — i'ligel Sound lo l.ower California; lOnj^land ((ariuMitcr). 



I'leistoccne. — San Pedro (Arnold). 



Family .\.W. K KLLlEi.LlD.K. 



CJeniis Aligena //. U. Lea. 



SlitU roiindeii, lri;iiij>u];ir, inlUitcd; single small anterior tooth under the beaks, separated 

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

 resiliuni carrying a lithodisnia. 



ry[)c, Ali(/c>iii !<tii(it(t (Lea). 



70. Aligena cerritensis, sji. nov. 

 Pi.ATK XIII, Fiii. 3. 



Shell small, ruuniled, triangular, inllated, ihiii; inecjuilateral, the umbo being nearly lirminal 

 posteriorly; anterior dorsal margin nearly straight; anterior extremity quite sharply roundcil and 

 proiluced furthest below middle; (josterior e.xtremity sloping ofT abruptly from umbo ami rounded 

 near base; ventral margin arcuate; surface with faint concentric sculptuie; umbone.s small, pointed, 

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

 scars subeepial. 



Dimensions. — Long. 8.5 nmi.; all. >S mm.; iliani. 5 mm. 



This species rcseml)lcs Aclla amtrensis in ontline. Specimens identilied l>y 

 L)v. Dall, who pronounced it a new species. 



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

 is tiie lype, which is figured, and is now in liic I'nited States National Museum. 



Pleistocene. — San Pedro (Arnold). 



Supcrfamily C'.\K1)1.\L i;.\. 



Family XXVL CAKDIID.E. 



Genus Cardium (Linmj LunMrclc. 



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

 or gaping but slightly, with no kmule or escutcheon ; pallial line rather distant from the margin of 

 the valves. 



Subgenus Trachycardium Murck. 



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

 granulose ; left cardinals anterior when interlocked. 



Type, Cardium isocardin (Linne). 



