1888.] NATURAL SCIEKCES OF PHILADELPHIA. 119 



solid and curved ; dorsal cicatrices four, well impressed and situated 

 under the base of the anterior end of the lateral teeth which continue 

 almost to the cardinal teeth. 

 Diameter 1.3. Length 2.00. Breadth 3| inches. 



Habitat. Lake Woodruff, Volusia Co., Florida. 



Mus. Acad. Nat. Sci. Phihx. Coll. of Berlin H. Wright and 

 ]\rr. W. A. Marsh, Aledo, Illinois. 



Remarks. This species, though belonging to the Buckleyi group, 

 has specific characters distinguishing it from U. Buckleyi Lea ; the 

 adult is very excurvate on the basal margin, has a very smooth and 

 polished epidermis, filled with obscure rays, the anterior end being 

 directed obliquely upwards, characters not pertaining to adult U. 

 Buckley i. The symmetry of the dorsal and basal curves is peculiar, 

 being in this character like the same curves of U. symmetricus Lea. 

 Its affinity is with U. Buddianus Lea, differing in the teeth and 

 other characters. Dedicated to Mr. Wm. A. Marsh, of Aledo Illinois, 

 an amateur of the Unionidae. 



TJnio Dallii. Plate VI, fig. 1. 



Shell ovate, pointed and flattened behind, the point being directed 

 downward, in an uncinate manner. Polished above, and lustreless 

 below, valves not thick, thicker before, epidermis black, rayless, 

 with numerous strise of scaly plicss below the umbonial region. Lig- 

 amental margin much arched, with an angle at each end. Posterior 

 margin usually slightly and evenly convex. Basal margin emar- 

 ginate near the posterior end, anterior margin nearly truncated, or 

 abruptly rounded. Umbonial slope very depressed, obtuse and 

 scarcely carinate, and the sides of the valves are decidedly flattened 

 just forward of the umbonial slope. Greatest diameter in the mid- 

 dle of the shell. Umbos broad and flattened, obtuse, projecting, 

 and vei'y much eroded. Sides with numerous close coarse lines of 

 growth. Nacre salmon or pink, varying to copper color, iridescent 

 and usually with wax-colored spots, which often are confluent and 

 cover the interior. Cavity of the shell, and of the beaks shallow. 

 Lateral teeth long, heavy and much curved. Cardinal teeth coarse, 

 deep, divergent. Anterior cicatrices distinct, the . larger are deep. 

 Posterior cicatrices confluent, well impressed. The type specimen 

 is about two-thirds the full size. 

 Diameter 1.00. Length If. Breadth 1h inches. 



Habitat. Lake Beresford, Volusia Co., Florida. 



Mus. Acad. TSTat. Sciences. Newcomb Coll. National Museum. 



