328 



et prope ligamentum magnum iuciso; extremitate antica rotun- 

 data ; costa umbonali magis mimisve conspicua ; dentibus prima- 

 riis distinctis ; margine cardinali sub ligamento iiitus incrassato, 

 superticie interna impolita. 



Testa seniore obovali, tequilaterali ; margine dorsali subliorizon- 

 tali, convexiusculo ; latere antico lato ; extremitate postica obtusa ; 

 margine postico angulum obtusum cum margine ventrali formante ; 

 ligamento maximo. 



Tedd jimiore siciit in seniore, sed ovali, inaequilaterali ; margine 

 dorsali antico subdecli\T[ ; latere antico longiore, attenuate. 



Var. Testa ovali, ineequilaterali, margine dorsali antico subde- 

 clivi ; latere antico longiore, plerumque ad extremitatem attenuate ; 

 extremitate postica angulata; margine ventrali postice subiucur- 

 vato et magis sursum acclinato. 



Inequivalve, tolerably strong, smooth, glossy, rounded in front; 

 one valve convex, tlie other flattened ; ventral margin subarcuated ; 

 dorsal edges not greatly sloping, near the large ligament (under 

 wliich the liinge margin is internally thickened) with an incision ; 

 umbonal ridge more or less conspicuous ; teeth distinct. 



Adult. Oboval, equilateral, hinge-margin subhorizontal and 

 slightly convex; anterior side broad; hinder extremity obtuse; 

 posterior edge forming one obtuse angle ^ith the ventral ; ligament 

 very large. 



Young. Resembling the adult, but oval and inequilateral ; the 

 front dorsal edge moderately sloping; anterior side the longer, 

 attenuated at its termination. 



Var. Oval, inequilateral ; fi'ont dorsal edge moderately sloping ; 

 anterior side the longer, and generally attenuated at its extremity ; 

 posterior end angulated, the hinder ventral edge being somewhat 

 incurved and sloping upward. 



California. 



To this section belong, likewise, the T. lateralis and brevifrons 

 of Say, which, however, I am miable to identify ; and as the species 

 have not been recognised by any subsequent conchologists, and 

 are unkno^^Ti even to the natui-ahsts of the United States, I 

 cannot, consequently, add to descriptions which will not exactly 

 apply to any Tellens I am acquainted with. 



" Tellina lateralis, Sai/, Joum. Ac. Nat. Sci. Plulad. 

 Transversely subovate, subequilateral ; posterior (anterior) mar- 



