unionidjR. 489 



Sub-gen. glans, Miihlfeldt. 



Shell trapeziform, with radiating, crenulated ribs ; margin of 

 valves plicate. 



naviformis, Reeve. trapezia, Linn. 



Sub-gen. thecalia, H. and A. Adams. 



Shell oblong, radiately ribbed; interior of valves folded on 

 themselves, forming a receptable for the ova. 



concamerata, Chem. 



Genus LAZARIA, Gray. 



Shell transversely oblong, strongly costate. Hinge with 

 the front cardinal tooth compressed; anterior lateral tooth 

 distinct. 



Ex. L. radiata, Broderip, pi. 116, fig. 4, 4, a. 



The genus Lazaria comprises but few species, chiefly 

 from Madagascar and South America. 



Species of Lazaria 



affinis, Brod. pectunculus, Brag. 



Californica, Desk. radiata, Brod. 



gracilis, Shuttl. 



Fam. UNIONID.E. 



Labial palps wider than long, usually united as far as the 

 middle of their hind margins. Mantle-lobes entirely dis- 

 united, not produced into siphonal tubes, the branchial 



