DESCRIPTIONS OF 



Unio Rowellii. pi. 40, fig. 136. 



Testa sulcata, elliptica, subinflata, postice obtusfe angulata, inaequilaterali ; valvulis subcrassis, anticfe 

 paulisper crassioribus ; natibus prominulis, ad apices undulatis ; epidermide rufo-fusca, obsolete 

 radiata ; dcntibus cardinalibus compressis, elevatis, crenulatis, in utroque valvule duplicibus ; laterali- 

 bus subrectis sublongisque ; margarita alba et iridescente. 



Shell sulcate, elliptical, rather inflated, obtusely angular behind, inequilateral ; 

 valves rather thick, a little thicker before ; beaks slightl}^ prominent, undulate at the 

 tips ; epidermis reddish brown, obsoletely radiated ; cardinal teeth compressed, 

 raised, crenulate, double in both valves; lateral teeth nearly straight and rather 

 long ; nacre white and iridescent. 



Un!o RoKcUH, Lea. Proc. Acad. Nat. >Sci., 1859, p. 15o. 



Hah. — Chargres River, New Granada. Rev. Joseph Rowell. 



My cabinet and cabinet of Wm. Cooper, Esq. 

 Diam. 'G, Length 1, Breadth VI inch. 



Shell sulcate, elliptical, rather inflated, obtusely angular behind, inequilateral ; 

 substance of the shell rather thick, thickened before ; beaks slightly prominent^ 

 minutely undulate at the tip; ligament rather short, somewhat thick and light 

 brown ; epidermis reddish brown, inclining to olive, obscurely rayed ; umbonial slope 

 slightly raised and rounded ; posterior slope very slightly raised, with two obscure, 

 impressed lines on each valve, from the beaks to posterior margin ; cardinal teeth 

 compressed, raised, crenulate, double in both valves ; lateral teeth nearly straight and 

 rather long ; anterior cicatrices distinct and well impressed ; ix)sterior cicatrices con- 

 fluent ; dorsal cicatrices placed under the plate, posterior to cardinal teeth ; cavity of 

 the shell I'ather deep a.nd rounded ; cavity of the beaks rather deep and subangular ; 

 nacre white and iridescent. 



Remarks. — In outline this species is very near to Oregonensis, (nobis). It is, how- 

 ever, of a more narrow ellipse and differs in being sulcate. The nacre is essentially 

 white, but in a few specimens there is a disposition to a yellowish tint. It is also 

 allied to Goascoranensis, (nobis), but it is not so thin and compressed, while in outline 

 it is very nearly of the same ellipse. The undulations of the tips are small and few. 

 This species is dedicated to the reverend gentleman who discovered it. I owe the 

 possession of several specimens to my friend Judge Cooper, who received them from 

 the Rev. Mr. Rowell. 



Unio Wilsonii. PI. 40, fig. 137. 



Testa erebi-e et leviter sulcata, transverse elliptica, subinflata, valde inawiuilaterali ; valvulis tenuibus j 

 natibus prominentibus, ad apices laevibus; epidermide olivo-vit-ideseente, nitida, obsolete radiata; 

 dentibus cardinalibus parvis, lamellatis et obliquis ; lateralibus longis, acicularis subrectisque > 

 margarita caerulco-alba ct iridescente 



