44 NEW UNIONID.E OF THE 



Maegaritana Elliottii. pi. 31, fig. 108. 



Testa IfBvi, elliptica, inflata,, postice subrotunda, inequilateral!; valvulis subtenuibus, anticd crassioribus ; 

 natibus prominulis, ad apices paulisper undulatis ; epidermide micante, radiata, vel viridi vel tenebroso- 

 fusca; dentibus cardiualibus parvis, compressis, in utroque valvule unicis; margarita, cserulea et 

 iridescente. 



Shell smooth, elliptical, inflated, subrotund behind, inequilateral ; valves rather 

 thin, thicker before ; beaks a little prominent, slightly undulate at the tips ; epidermis 

 shining, radiated, greenish or dark brown ; cardinal teeth small, compressed, single 

 in both valves; nacre bluish and iridescent. 

 Proc. Acad. Nat. Sci., 1858, p. 138. 



Hah. — Chattahoochee Eiver, near Columbus, Georgia, Bishop Elliott. 



My cabinet and cabinets of Bishop Elliott, Dr. Lewis and G. Hallenbeck. 

 Diam. "7, Length 1, Breadth 1*7 inches. 



Shell smooth, elliptical, inflated, rounded Ijehind, inequilateral ; su1)stance of the 

 shell rather thin, thiclcer before ; beaks a little prominent, with several sulsconcentric 

 undulations at the tips; ligament short, thin and light brown; epidermis shining, 

 broadly rayed, greenish or dark brown; umbonial slope raised and rounded; cardinal 

 teeth small, compressed, single in both valves; anterior cicatrices confluent and 

 very slightly impressed ; posterior cicatrices confluent and very slightly impressed ; 

 dorsal cicatrices placed across the base of the cardinal tooth and within the cavity of 

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

 subangular; nacre bluish and iridescent. 



Soft parts. — Branchial uterus . All the three specimens in alcohol seem to be 



males. There were no ova to be found. Branchiw large, nearly semicircular, inner 

 ones the larger, free two-thirds of the abdominal sack. Paljn large, suboval, united 

 one-third down the posterior edges. Mantle thin, thickened at the margin, maculate 

 with brown on the posterior outward edges and crenulate below the branchial opening. 

 Branchial opening rather small, with numerous small light brown papilla3. Aiial 

 opening small, with numerous and very small papillae on the inner edges. Super-anal 

 openiiig small, united for some distance below, with brown spots on the outer edges. 

 Color of the mass whitish. 



Remarks. — It is to be regretted that 1 could not have the advantage of seeing the 

 female with her charged branchial uterus. There is a resemblance to Margaritana 

 viarginata in the square spotted marks on the outer edges of the mantle and in the 

 form of the teeth, but it is by no means so stout a shell, nor has it the same kind of 

 rays, nor is it angular on the umbonial slope. 



This is a well characterised species. In the outline and in the rays it is very 

 like A. Ferussaciana (nobis), but the green rays are more abundant and usually they 

 cover the whole disk, leaving thin rays of yellow between. The old specimens become 



