198 NEW -UNIONIDiE OF THE 



My cabinet and cabinet of Mr. Anthony. 

 Diam. - 9, Length l - 4, Breadth 2-3 inches. 



Shell smooth, elliptical, inflated, slightly flattened at the sides, obtusely biangular 

 behind, rounded before, inequilateral ; substance of the shell rather thin, slightly 

 thicker before; beaks somewhat prominent; ligament rather long, somewhat thick 

 and brown; epidermis yellowish olive, without rays, shining, with rather distant 

 marks of growth ; umbonial slope raised into a somewhat acute angle ; posterior slope 

 wide, elliptical, subcarinate, darker than the side and furnished with corrugate folds ; 

 cardinal teeth small, oblique, slightly compressed, striate and crenulate ; lateral teeth 

 long, lamellar and somewhat curved ; anterior cicatrices distinct, rather large and well 

 impressed ; posterior cicatrices confluent, large and slightly impressed ; dorsal cica- 

 trices placed under the plate over the cavity of the beaks ; cavity of the shell rather 

 deep and wide ; cavity of the beaks somewhat deep and obtusely angular ; nacre 

 bluish white and iridescent. 



Remarks. — A single specimen only is before me, and this is so imperfect at the 

 beaks as to preclude a knowledge of the undulations of the tips. I know of no spe- 

 cies which this closely resembles. At first view it reminds one of Margaratina 

 marginata (Alasmodonta marginata, Say,) having a broad posterior slope with corru- 

 gate folds, but it has not the colored markings of the species on the sides. In the 

 teeth of course they entirely differ, Anthonyi having regular, large, lamellar lateral 

 teeth. With a single specimen it is very difficult to decide upon unusual characters. 

 The specimen before me has irregular scattered corrugate folds on the whole of the 

 posterior slope, which, if persistent and increased in size in most individuals, would 

 properly place it in the plicate group. The epidermis of this specimen has been 

 varnished, and some of its characters injured thereby, giving it a false polish and 

 plastering down the striae which usually exist along the basal margin. In this speci- 

 men the lines of growth are four. I name it after Mr. J. G. Anthony, to whom I 

 am indebted for the specimen. He mentions having received five or six individuals 

 from Florida. 



Unio Riddellii. PI. 27, fig. 267. 



Testa lasvi, subtriangulari, valde inflata, ad umbones tumida, postice obtuse angnlata, autice rotunda, 

 subsequilaterali • valvulis crassis, antice paulisper evassioribus ; natibus valde promincntibus, 

 incurvis, ad apices plicis parvis indutis; epidcrmide fusco-oliva, obsolete radiata; dentibus cardi- 

 nalibus parviusculis, subpyramidatis corrugatisque ; lateralibus crassis, corrugatis, curtis subcurr- 

 isque ; margarit& alba et iridescente. 



Shell smooth, subtriangular, very much inflated, swollen at the umbones, obtusely 

 angular behind, round before and subequilateral ; valves thick, slightly thicker 

 before; beaks very prominent, incurved, covered at the tips with small folds; epi- 

 dermis brownish olive, obscurely radiate ; cardinal teeth somewhat small, subpyra- 



