136 THE NAUTILUS. 
CONTRIBUTION TO A KNOWLEDGE OF UNITED STATES UNIONIDE. 
BY 8S. HARP WRIGHT. 
Unio Pinkstonii sp. noy. 
Shell flask-shaped or triangular, clavate, inflated below the beaks, 
rounded anteriorly and very bluntly pointed behind. Epidermis 
olive with transmitted light, with numerous close lines of growth ; 
rayless. Beaks elevated, blunt and nearly on a line with the an- 
terior margin in old specimens, but the shell very inequilateral in 
the young. Sides very convex and descending in front very 
abruptly. Basal margin very convex. Umbonal ridge very blunt, 
and only slightly raised. Posterior slope narrower, its margin not 
keeled. Cavity of shell deep, cavity under the beaks slight, bluntly 
rounded. Cardinal teeth erect, striate; the anterior cardinal trun- 
cate. Cardinal in right valve single. Cavity between cardinals 
with a deep conical pit. Lateral teeth straight and short. Dorsal 
cicatrices over the beak-cavity. Nacre white, without iridescence, 
except at the posterior end, where the nacre is thin, it being thick 
elsewhere. Cicatrices all distinct and well-impressed. Width 13 
inches, length 13, diameter 1. 
Habitat: Tuscaloosa River, Macon Co., Ala. 
Remarks: Affinity, U. castaneus Lea, from which it differs in 
having a tray-shaped cavity, instead of bowl-shaped, as in the former. 
Its rings of growth are low and fine, not ridgy and coarse as in old 
U. castaneus. The U. nux group probably includes this and U. cas- 
taneus, U. concolor, U. brumbyanus and U. perovatus, species more 
or less related to our shell, in which the nacre is laid unevenly in 
plates and ridges, which form two or more pits where they meet. 
The species is dedicated to Miss M. 8. Pinkston, who assiduously 
collects Unionide, and found this among her collections. 
Unio Kirklandianus sp. nov. 
Shell ovate, brilliantly polished, rather thin and somewhat in- 
flated. Sides dilated in the middle and attenuated at each end. 
Base very convex; anterior end rounded and the other bluntly 
pointed. Epidermis yellowish horn-color, with broad green rays on 
all the surface, which are interrupted near the base with narrow 
yellow bands. Lines of growth only two or three and ferruginous. 
Beaks blunt and broad, slightly raised; umbonal ridge raised and 
abruptly rounded. Posterior area abrupt, narrow and slightly 
