1888.] NATURAL SCIENCES OF PHILADELPHIA. 115 



Remarks. This species has the general form of U. Emmonsii Lea, 

 and is more in affinity with that species, than with U. Shepherdianus 

 Lea. The former is a much heavier species, and with coarse heavy 

 teeth. U. Shepherdianus Lea, is deeply emarginate on its basal 

 margin, and the sides of its valves are very much constricted ob- 

 liquely from its projecting umbos down, while U. Waltoni, is very con- 

 Tea; in its basal Jiiargiu and its umbos not projecting, and its anterior 

 end very obliquely rounded, instead of evenly rounded, and a thin 

 shell. It can not be confounded with U. perlatus, Lea, though the 

 obliquity of the anterior end is much alike in both. It is witli much, 

 pleasure that we name this curious species, after Mr. John Walton, 

 a zealous and working conchologist, and artist of Rochester N. Y. 



TJnio Dorei. Plate III, fig. 1, 



Shell ovate, heavy; polished, rayless; epidermis reddish, with 

 brownish colored elevations or growth-ridges; beaks blunt and mas- 

 sive, dorsal margin very broad, short and slightly arched; posterior 

 margin quite straight; Umbonial angle sharp and supplemented by 

 two parallel elevations which are more or less broken by undulations; 

 basal margin slightly rounded, anterior margin truncate and angu- 

 lated above; cardinal teeth with a tendency to being double in both 

 valves, very massive, smoothish; lateral teeth very long, heavy and 

 uniformly curved; nacre a rich salmon color; cavity of the beaks 

 almost wanting: of the shell considerable. Named for Mr. H. E. 

 Dore, and enthusiastic collector of mollusca of Portland Oregon. 



Diameter 1.25. Length 1.6. Breadth 2.60 inches. 



Habitat. Lake Monroe, Florida. 



Mus. Acad. Sciences ; Coll. B. H. AV right. 



Bemarks. The affinity of this species is with U. Conasaugaensis 

 Lea, but the teeth differ, the umbos of the latter are not so broad 

 and blunt, anrl are farther from the anterior end, and has a white 

 nacre. Tliere is much disparity between it and U. Bucklyi Lea. 



Unio Averellii. Plate ITI, fig. .1. 



Shell obovate, thin, fragile, slightly inflated, inequilateral, smooth^ 

 polished, interrupted by numerous green capillary rays arranged in 

 fascicles which are narrowest at the anterior end of the shell, and broad- 

 en gradually until near the umbonial angle where they merge together, 

 giving the posterior portion of the shell a dark green color; epider- 

 mis yellowish; beaks flattened, rather blunt, slightly and coarsely 

 undulated; dorsal margin nearly straight; ligament short, horn 

 colored, thin; anterior margin short and gracefully rounded; posterior 



