CONCHOLOGICAL WRITINGS. 91 



1 Sp. PI. lateridria R. fig. 2. Shell oblong, small side smooth, 

 longer side with 5 transversal furrows, axis far behind, length one 

 third of breadth — In petrosilex, one inch long. 



2 Sp. PL divisa R. Shell oblong divided in the middle by a large 

 furrow and small sinus at the end of it, 5 curved ribs on the small 

 side, t on the large divided by deep furrows, small side rounded, 

 longer attenuate, axis proeminent submedial, length half of breadth. 

 In grey petrosilex, over one inch. 



3 Sp. PL anisocta Raf. Shell swelled rounder, a deep furrow in 

 the middle, 8 curved unequal ribs, 4 on each side, small side round, 

 longer side truncate, beak proeminent submedial, length 3-4ths of 

 breadth. In variegated petrosilex, about one inch. 



4 Sp. PL latiundata R. fig. 6. Shell oblong both ends obtuse, 3 

 [143] 



or 4 broad waved ribs, margin flexuose, beak submedial, length 2-5 



of breadth. With the last larger. 



5 Sp. PL striata R. Shell oblong, swelled both sides rounded, 

 hinge flexuose by arched beak, equal longitudinal strias throughout, 

 beak submedial, length half of breadth. In white sandstone, nearly 

 two inches. 



6 Sp. PL hifasciata R. fig. 4. Shell rounded swelled, smooth 

 with two faint transversal bands or wrinkles, beak round lateral, 

 length 2-3ds of breadth. In yellow sandstone, small, half an 

 inch. 



1 Sp. PL concentrica R. fig. 5. Shell oval, minute concentric 

 strias, beak obtuse at 1-3, sides rounded, length 2-3ds of breadth. 

 In petrosilex. 



8 Sp. PL obliqua R. fig. 3. Shell oval oblique swelled, 8 carved 

 oblique furrows, 3 and 4 on the sides of. the middle one, beak pro- 

 eminent at 1-3, length 2-3 of breadth. In grey chert or uetrosilex, 

 small half an inch, near to sp. 3, but less deeply furrowed not trun- 

 cate behind. 



[From the Atlantic .Toumal and Friend of Knowledge. No. IV., page 154. 



Philadelphia, 1832.] 



[154] 

 CoNCHOLOGY. Two New Bivalve Fluviatile Shells of S. 



America, By C. S. Rafinesque. 



These two fine shells are from the Cabinet of Professor Green, 

 who permitted me to draw them and describe last March. They 

 are both from the R. Parana above Buenos Ayres. 



