CHIEFLY OF THE UNITED STATES. 7 



BemarTcs. — About a dozen specimens are before me. The old ones are dark brown, 

 and have lost their rays. The younger ones have a yellowish or reddish ground, with 

 numerous green rays and rather well marked lines of growth. Most of the specimens 

 have a a white nacre, some are purple, and one is inclined to salmon color in the cavity 

 of the beaks. This is one of the complanatus group and the younger specimens remind 

 one of Congareus, (nobis), but it is a much larger species, is darker, and has not the high 

 polish of epidermis, and is not so angular on the umbonial slope. None of the speci- 

 mens were perfect enough at the beaks to observe the character of the undulations. 



Unio aberrans. pi. 1, fig. 3. 



Testa lavi, oblonga, subinflata, vakle inEequilaterali. ad latere planulata, postice obtusa biangulata, antice 

 rotundata; valvulis crassiusculis, antice crassioribus ; natibus subprotninentibus ; epidermide luteo- 

 fusca, valde radiata ; dentibus cardinalibus parvis ; in utroque valvule duplicibus ; lateralibus longis 

 laniellatis subrectisque ; margarita caeruleo-alba vel purpurea et iridescente. 



Shell smooth, oblong, somewhat inflated, very inequilateral, flattened at the sides, 

 obtusely biangular behind and rounded before ; valves somewhat thick, thicker be- 

 fore ; beaks somewhat prominent ; epidermis yellowish brown, very much rayed ; 

 cardinal teeth small and double in both valves ; lateral teeth long, lamellar and 

 nearly straight ; naci'e bluish white or purple and very iridescent. 

 Proc. Acad. Nat. Sci., 1863, p. 191. 



Hab. — Neuse Kiver, six miles east of Raleigh, North Carolina, E. Emmons, M. D. 



My cabinet and cabinet of Dr. Emmons. 

 Diam. '9, Length 1-4, Breadth 2' 7 inches. 



Shell smooth, oblong, somewhat inflated, very inequilateral, flattened at the side, 

 obtusely biangular behind, rounded before ; substance of the shell a little thick, 

 thicker before ; beaks somewhat prominent ; ligament rather large and dark brown ; 

 epidermis yellowish brown, with numerous oblique green rays and with rather distant 

 marks of growth ; umbonial slope somewhat raised and angular ; posterior slope 

 rather narrow and carinate ; cardinal teeth small, compressed, striate, crenulate, 

 oblique and double in both valves ; lateral teeth long, lamellar and nearly straight ; 

 anterior cicati'ices distinct, rather large and well impressed ; posterior cicatrices conflu- 

 ent, large and slightly impressed ; dorsal cicatrices placed above the centre of the 

 cavity of the beaks ; cavity of the shell rather deep and wide ; cavity of the beaks 

 shallow, and obtusely angular ; nacre bluish white or purple and iridescent. 



Remarhs — This species is nearly allied to Raleigheiisis, herein described. It may 

 be distinguished by its greater width, its being thinner, and it differs in the cardinal 

 teeth. Three of the four specimens before me are white, and one is purple. None of 

 the beaks were perfect enough to observe the character of the undulations of the tips. 



