﻿UNITED STATES AND NORTHERN MEXICO. 353 



Unio fucatus. PI. 59, fig. 178. 



Testa lasvi, elliptica, subinflata, valde incequilaterali, postice subbiangulata, antice rotundata ; valvulis tenui- 

 bus, antice 1 paulisper crassioribus ; natibus prominulis, ad apices undulatis ; epidermide olivo-lutea, 

 micante, undique virido-maculata ; dentibus cardinalibus parvis, compresso-conicis, crenulatis, in utroque 

 Talvulo duplicibus; lateralibus longis, lamellatis pubcurvisque ; margarita vel ca?ru!ea vel luteo-alba 

 et valde iridescente. 

 Shell smooth, elliptical, somewhat inflated, very inequilateral, subbiangular behind 

 and rounded before ; valves thin, a little thicker before ; beaks slightly prominent 

 undulate at the tips ; epidermis olive yellow, shining, spotted with green all over ; 

 cardinal teeth small, compressed-conical, crenulate and double in both valves; lateral 

 teeth long, lamellar and somewhat curved ; nacre bluish or yellowish white and very 

 iridescent. 



Proc. Acad. Nat. Sci. I860, p. 92. 

 Bab. — North Alabama, Prof. Tuomey ; Tuscumbia, L. B. Thornton, Esq. 

 My cabinet and cabinets of Mr. Thornton and Mr. Pybas. 

 Diam. -6, Length 1*2, Breadth 2-1 inches. 



Shell smooth, elliptical, somewhat inflated, very inequilateral, subbiangular behind 

 and rounded before ; substance of the shell thin, a little thicker before ; beaks slightly 

 prominent, undulate at the tips ; ligament rather long and dark brown ; epidermis 

 olive yellow, shining, spotted with green all over and with distant marks of growth ; 

 umbonial slope raised and rounded ; posterior slope slightly carinate ; cardinal teeth 

 small, compressed-conical, crenulate and double in both valves; lateral teeth long 

 lamellar and somewhat curved ; anterior cicatrices distinct and well impressed ; pos- 

 terior cicatrices confluent and slightly impressed ; dorsal cicatrices in a row under the 

 plate and across the base of the cardinal tooth ; cavity of the shell shallow and wide ; 

 cavity of the beaks very shallow and subangular ; nacre bluish or yellowish white and 

 very iridescent. 



Remarks. — I have seven specimens of this species before me. Two from the late 

 Prof. Tuomey and five from Mr. Thornton. It is closely allied to pidus (nobis), and 

 to ornatus herein described. I had considered it as a variety of ornatus, but I am now 

 satisfied that it is a distinct species. It differs in being thinner and lighter, and in 

 being more inflated as well as in being a smaller species. The small green spots are 

 more frequent and the lines of growth are fewer and more distant. In the lines of 

 growth and some other characters it resembles canielqpardilis herein described, but it 

 is not so transverse, not quite so much inflated, nor are the spots so large or so square. 

 In outline it is very near to tener (nobis). Like all the species of this group while 

 the nacre is generally white throughout, there is a disposition to a yellow tint and 

 sometimes a purplish one, in the thickened parts. Among the seven received one is 

 purplish and two or three yellowish. In some of the specimens there is a slight 

 emargination on the upper portion of the posterior margin. 



90 



