CONCHOLOaiCAL WRITINQa. 69 



with concentric wrinkles, large valve with a depression and sinus. 

 Length 4-5, thickness 2-5 of the breadth. From the limestone of 

 Lake Erie and Ohio, silicified blackish, about one inch. 



38. STROPHOMENBS, Raf. 1820. See tract of October. 1. 

 Str. levigata. Very smooth, longer valve convex, lower valve con- 

 cave, corners acute, not auriculate, contour arched and even. Length 

 4-5 of the breadth. Kentucky limestone. 2. Str. flexilis. Very 

 thin, lower valve hardly concave with minute curved strias, upper 

 valve convex with minute flexuose strias, corners acute subauriculate, 

 length and breadth equal. Limestone of Ohio, 1 or 2 inches. 



40. CTJRVULITES, Raf. 1819. Inequilateral, inequivalve, valves 

 elohgatedj curved or crooked, larger valve broader, the smaller often 

 angular. 1. G. striata, Raf. 1818. Cnneate curved, base narrow, 

 end broad rounded, striated longitudinally, short alternate strias near 

 the end. In the Kentucky limestone, 2^ inches. 



41. ZONARITES, Raf Tribe of Atremosia or imperforated 

 Terebratulites. Shell subtransversal equilateral, subinequivalve, 

 both valves convex with thick concentric wrinkles, hinge linear, beaks 

 very small. 1. Z. atrata. Nearly rounded, with large wrinkles and' 

 furrows between. Length 5-6 of the breadth, thickness nearly half. 

 Perfect black shell silicified, nearly one inch, from the Knobhills, 

 disc, in 1822. 



42. Zonarytes? Tesselata, Raf. Rounded, tesselated by concen- 

 tric and longitudinal wrinkles and furrows. Length 7-8 of the breadth. 

 From the Knobhills, one inch broad, has only 1 valve incrusted in 

 quartz, and with the hinge too imperfect to refer it decidedly to 

 this Genus. 



[Continuation of a Monograph of the Bivalve SljeUs of the River Ohio, and 

 other Rivers of the Western States. By Prof..C. 8. Rafinesque. (Pub- 

 lished at Brussels, September, 1830. J Containing 46 Species, from No. 76, 

 to No. 131. Including an Appendix on some Bivalve Shells of the Rivera 

 of Hindoatan, with a Supplement on the Fossil Bivalve Shells of the 

 Western States, and the Tulosites, a new Genus of Fossils. Philadelphia, 

 October, 1831.] 



[1] 



Hardly a dozen species of North American fluviatile bivalve shells, 

 had been mentioned by Bosc. Lamark, Say, and Lesueur, before 

 1820, when I described, in a special and ample Monograph, lb 

 species of 'them 1 with 40 varieties, mostly discovered by myself, in 



