DESCRIPTIONS Ol' 



Unio melleus. pi. 38, fig. 129. 



Testa sulcata, elliptica, subinflata, valdfe inasquilatciali ; valvulis subcrassis, antic6 crassioribus ; natibus 

 subprominentibus, ad apices minute undulatis ; epidermide melina, obsolete radiata, nitida ; dentibus 

 cardinalibus subgrandibus, ereetis, crenulatis, in utroque valvule duplicibus; lateralibus sublongis, 

 subrectis, in utroque valvule duplicibus ; margarita salmonis colore tin eta et iridescente. 



Shell sulcate, elliptical, slightly inflated, very inequilateral ; valves rather thick, 

 thicker before ; beaks rather prominent and minutely undulate at the tips ; epidermis 

 honey yellow, obsoletely rayed and bright ; cardinal teeth rather large, erect, crenu- 

 late and double in both valves ; lateral teeth rather long, nearly straight and double 

 in both valves ; nacre salmon colored and iridescent. 



Unio melleus, Lea. Proc. Acad. Nat. Sci., 1859, p. 152. 



Eab. ? H. Cuming. 



Cabinet of Mr. Cuming. 

 Diam. -7, Length I'l, Breadth 2 inches. 



Shell sulcate, elliptical, slightly inflated, very inequilateral, obtusely angular 

 behind ; substance of the shell rather thick, thicker before ; beaks rather prominent, 

 minutelj' and beautifully undulate at the tips ; ligament rather short, thin and light 

 brown; epidermis honey yellow, obscurely rayed, bright, with furrows over nearly 

 the whole disk ; umbonial slope slightly raised and rounded ; cardinal teeth rather 

 large, erect, creuulate and double in both valves ; lateral teeth rather long, nearly 

 straight and double in both valves ; anterior cicatrices distinct ; posterior cicatrices 

 confluent ; dorsal cicatrices placed under the plate, posterior to the cardinal tooth ; 

 cavity of the shell rather shallow and rounded ; cavity of the beaks rather deep and 

 angular ; nacre salmon colored and iridescent. 



Reniarlcs. — There was no habitat attached to this specimen, a single one only being 

 sent to me by Mr. Cuming. It is nearest to aratus, (nobis), but is a much larger 

 species and is more oblique, and the color is more of a honey yellow. 



The most remarkable character of this shell is the double lateral tooth in the right 

 valve, which, indeed, is disposed to be trifid. That of the left is bifid as usual. The 

 anterior cicatrices are all three distinct and well impressed. This is very unusual. 

 These characters must be taken with some allowance, as we have but a smgle speci- 

 men yet to examine, and in others they may not be so well marked. 



Unio fluctiger. PI. 39, fig. 130. 



Testa perplicata,_subtransversa, compressa, vald6 insequilaterali, posticti subrotundata, ad basim subemar- 

 ginata; valvulis tenuibus ; natibus parvis, prominulis ; epidermide luteo-oliva, transversa et miuute 

 striata, eradiata; dentibus cardinalibus parvis, obliquis, compressis, in utroque valvule duplicibus; 

 lateralibus longis subrectisque ; margarita cseruleo-alba et iridescente. 



Shell plicate all over, rsither transverse, compres.sed, very inequilateral, rather 



