FRESH WATER AND LAND SHELLS. 77 



being obscured, and the whole epidermis is in a had state. In form it is somewhat allied 

 to U. obscurus, (Nobis,) but it cannot be easily confounded with that species, being more 

 compressed, and without rays. The lustre of the nacre is very beautiful. 



I name this after A. A. Gould, M D., of Boston, the able investigator of the Mollusca 

 of Massachusetts. 



Unio Estabrookianus. PI. VI. Fie. 17. 



o 



Testa Isevi, triangulari, valde compressas valvulis crassis; natibus prominulis, compressis, ad apices umlu- 

 lath: epidermide valde striata, luteo-fuscd, nitidd; dentibus cardinalibus cornpressis ; lateralibus brevis cras- 

 ■^ist/ue; marguritd alba et iridesccnti . 



Shell smooth, triangular, much compressed; valves thick; beaks slightly prominent, compressed and undulated 

 at the tips; epidermis much striated, yellowish-brown and shining; cardinal teeth compressed; lateral teeth short 

 and thick ; nacre white and iridescent. 



Hah. Clinch River and Second Creek, Tennessee. President Estabrook. 



My cabinet and cabinet of Mr. Estabrook. 

 Diam. .1. Length 2.2, Breadth 3.1 inches. 



Shell smooth, triangular, much compressed, nearly equilateral ; substance of the 

 shell thick before, thinner behind; beaks slightly prominent, compressed, minutely undu- 

 late at the tips; ligament rather short and thick; epidermis coarsely striated over the 

 whole disk, shining and ray less, the marks of growth being distant and regular; cardinal 

 teeth rather large, compressed and double in both valves; lateral teeth short and thick, 

 widely separate from the cardinal tooth, and in the direction of the apex; anterior cica- 

 trices distinct; posterior cicatrices distinct; dorsal cicatrices placed under the plate near 

 the cardinal tooth; cavity of the shell very shallow; cavity of the beaks very shallow and 

 rounded; nacre very white and iridescent. 



Rcmm-ks. — I dedicate this interesting species to President Estabrook, of Knoxvillc, 

 Tennessee, to whom I am indebted for a fine suite of species, and many other favours. 

 It is more nearly allied to I . rubiginosus, (Nobis,) than to any other species, but differs 

 in the coarse stria) and peculiar surface, which gives it the appearance of being varnished. 

 In the young, the epidermis has the yellow colour of U. /Esopus, Green, — in the mature 

 specimen it acquires almost a reddish-brown. The sides are remarkably flattened, and 

 the posterior ma ruin is disposed to be biangnlar. 



Unio Binnkyi. PI. VI. Fig. 18. 



Testa lievi, clliplicd, valde compressd, striata : valvulis subtenuibus ; natibus prominulis ; epidermide tene- 

 broso-fusca, nitida; <h,itil<>is cardinalibus parvis, compressis: lateralibus perlongis subcurvisque ; margarita 

 deo-albd tt iridescenle. 



Shell smooth, elliptical, much compressed, striated; valves rather thin; beaks slightly prominent ; epidermis 

 dark-brown, shining; cardinal teeth small, compressed; lateral teeth very long and rather curved; nacre bluUh- 

 white ami iridescent. 



Hab. Southern States. U. E. Griffith, M.D. 



Cabinet of Dr. Griffith. 

 Diam. .'i, Length 1.2, Breadth 2.1 incites. 



vol. x.— 20 



