60 NEW UNIONIDiE, MELANID^, ETC., 



thick, somewhat thickened before; beaks somewhat prominent, acuminate and 

 undulate at the tips ; ligament light brown, somewhat thick and short ; epidermis 

 yellowish, without rays and with rather distant marks of growth ; umbonial slope 

 somewhat raised and obtusely angular ; posterior slope narrow eUiptical and nearly 

 covered with small folds and corrugations; cardinal teeth compressed, corrugate, 

 crenulate and oblique ; lateral teeth long, lamellar, somewhat curved, single in the 

 right and double in the left valve ; anterior cicatrices small, distinct and well im- 

 pressed ; posterior cicatrices large, coniiuent and very slightly impressed ; dorsal 

 cicatrices placed within the cavity and near the base of the cardinal tooth ; cavity 

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

 obtusely angular; nacre pale salmon color, satin-like and very iridescent. 



Remarlcs. — A single specimen only of this pretty little species was received by 

 the Academy. It is very nearly allied to fluctiger, (nobis,) but it is a wider and. 

 larger species, and diflers in the form of the folds. Those m fluctiger combine near 

 the middle of the valve, and form angles pointing to the base of the shell, while 

 those of Natalensis combine on the umbonial slope and point to the posterior basal 

 margin. In outline it seems to be the same with U. Africanim, (nobis,) but the 

 specimen from which the description of Africanus was made has only a few undula- 

 tions at the beaks, which induced me to place it with the smooth group of Uniones. 

 When full suites may be obtained it is possible they may prove to be the same. In 

 the specimen of Natalensis before me the nacre is very rich, soft and satin-like, and 

 the small exterior undulations are plainly visible on the inside. 



Unio Paramattensis. pi. 20, fig. 59. 



Testa crebre et leviter sulcata, elliptica, subinflata, valde inrequilaterali, postice obtuse angulata, antice 

 rotundata ; valvulis crassiusculis, antice aliquanto crassioribus ; natibus prominulis, ad apices 

 radiis undulatis; epidermide tenebroso-fusca, nigricante, eradiata; dentibus cardinalibus parvis, 

 valde compressis, obliquis, valvulo dextro duplicibus ; lateralibus praelongis, lamellatis subrectisque ; 

 margarita alba et valde iridescente. 



Shell closely and finely sulcate, elliptical, somewhat inflated, very inequilateral, 

 obtusely angular behind and rounded before ; valves somewhat thick, slightly thicker 

 before ; beaks a little prominent, with radiating undulations at the tips ; epidermis 

 dark brown, blackish, without rays ; cardinal teeth small, much compressed, oblique 

 and double in the left valve ; lateral teeth very long, lamellar and nearly straight ; 

 nacre white and very iridescent. 



Proc. Acad. Nat. Sci., 1862, p. 176. 



Hah. — Paramatta River, New South Wales, Smithsonian Institution. 

 My cabinet and cabinet of the Smithsonian Institution. 

 Diam. -7, Length !•], ' Breadth 2 2 inches. 



