318 NEW UNIONIDiE, MELANID^, ETC., 



differs entirely from that species in being lenticular and not having the beaks much 

 raised. It differs also in the color of the epidermis, refulgens being of a very dark 

 chestnut-brown. The beaks will, I think, be found to differ. The specimens before 

 me have neither of the beaks perfect enough to display any undulations, which are 

 so marked and so beautiful in the verrucosus. The prominent characteristics of 

 refulgens are the lenticular form and the very remarkable nacre. In all the speci- 

 mens before me the inner portion of the nacre is pearly white, while the outer or 

 border portions are of a rich purple, the posterior part exhibiting an iridescence so 

 refulgent as to surpass any other species, in this respect, which I know. The younger 

 specimen has a broader purple border. The nodules in the specimens before me are 

 placed on the medial third of the disk, and are separate, unusually obtusely angular, 

 and pointing downward. On the posterior slope there are a few nodules. 



Unio Strebelii. PL 51, fig. 131. 



Testa Isevi, oblonga, ad latere compressa, inffiquilaterali, postice obtuse biangulata, antice rotundata ; 

 valvulis subcrassis, antice aliquanto crassioribus ; natibus prominulis ; epidermide luteo-fusca, 

 radiata; dentibus cardinalibus subcrassis, elevatis, erenulatis, in utroque valvule duplicibus ; 

 lateralibus sublongis, subcrassis, subcurvatis corrugatisque ; margarita vel purpurea vel salmonea 

 et valde iridescente. 



Shell smooth, oblong, flattened at the sides, inequilateral, obtusely biangular be- 

 hind and rounded before; valves rather thick and somewhat thicker before; beaks 

 a little prominent ; epidermis yellowish brown, radiate ; cardinal teeth rather thick, 

 raised, crenulate and double in both valves ; lateral teeth rather long, rather thick, 

 somewhat curved and corrugate ; nacre purple or salmon colored and very iridescent. 

 Proc. Acad. Nat. Sci. 1866, p. 133. 



Eah. — Vera Cruz, Mexico, G. Strebel, M. D. 



My cabinet and cabinet of Smithsonian Institution. 

 Diam. 1, Length 1-6, Breadth 2-9 inches. 



Shell smooth, oblong, flattened at the sides, inequilateral, obtusely biangular behind 

 and rounded before ; substance of the shell rather thick, somewhat thicker before ; 

 beaks a little prominent ; ligament large, rather short and dark brown ; epidermis 

 yellowish brown, radiate and with distant marks of growth ; umbonial slope slightly 

 raised and rounded ; posterior slope narrow elliptical, slightly carinate ; cardinal 

 teeth rather thick, raised, crenulate and double in both valves; lateral teeth rather 

 long, somewhat thick, somewhat curved and corrugate ; anterior cicatrices distinct, 

 somewhat large and well impressed ; posterior cicatrices confluent, large and slightly 

 impressed ; dorsal cicatrices placed in a row near to the centre of the cavity of the 

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

 and obtusely angular; nacre purple or salmon color and very iridescent. 



