1888.] NATURAL SCIENCES OF nilLADELPHIA. 117 



Bemarhs. This beautiful shell was found by Mr. J. B. U})sor/ 

 several years ago. Its affinity is with U. cornetts Lea, and witli C7. 

 Fostellii Lea. From the hitter itdifiersin not having a striated and 

 scaly epidermis, and in not having thick, but con;pressed cardinal 

 teeth. The former has much heavier teeth, the groove of the lateral 

 teeth being shorter and much farther from the cardinal teeth, and 

 the beaks farther from the anterior end, and the post-ligamental area 

 much more conspicuous. It can not be taken for U. jAan'dateris 

 Con. which has a stramineus epidermis. 



We name this peculiar species for Dr. Edw. J. Nolan, Librarian, 

 to the Academy of Natural Sciences of Philadelphia. 



Unio Hinkleyi. Plate IV, fig. 2. 



Shell oblong, trapezoidal, attenuated and pointed behind, smooth,, 

 slightly inflated, and often flatish ; rather thin, polished above. 

 Epidermis black, thickly covered with brown, indistinct fine rays, 

 visible with transmitted light. Posterior margin subemargiuate, 

 raised into a compressed wing. Anterior margin rounded and slightly 

 oblique. Dorsal margin a slightly arched curve. Basal margin, 

 slightly convex. Umbonial slope raised and obtusely rounded^ 

 Cardinal teeth compressed, thin, very oblique and grooved, double 

 in both valves. Lateral teeth very long, slender and undvdating, 

 nearly straight. Dorsal cicatrices four or more in one or two 

 rows. Nacre pinkish, and iridescent. Umbonial region broad and 

 blunt, very slightly projecting, but often deep. 

 Diameter 1.00. Length 1.50. Breadth 3.00. 



Habitat. Lake Monroe, Florida. 



Mus. Acad. Nat. Sciences. National Museum. 



Remarks. In outline this species is similar to that of U. deelivis- 

 Say, but its black epidermis, its pinkish or purplish nacre, readily 



distinguishes it from that species. 



It is dedicated to Mr. A. A. Hinkley, of Dubois Illinois, an ac- 

 tive collector of Unionidse. 

 Unio Simpsoni. Plate V, fig. 1. 



Shell oblong-ovate, pointed behind, and often very slightly unci- 

 nate below the point, inequilateral, remarkably smooth and polished. 

 Valves thin, slightly inflated, and rarely with a few coarse, perpen- 

 dicular, impressed grooves near the centre. Sometimes the valves 

 are very flat. Ligamental margin higher behind, and straight 

 or slightly arched. Posterior slope biangular below, straight or 



