142 PALAEONTOLOGY OF KENTUCKY. 



Streptorhynchus temris HALL. 



Streptorhynchus tennis, Hall. Trans. Alb. Inst., Vol. 4, p. 210 18(53. 

 Streptorhynchus tennis, Hall. 28th Regent's Kep., p. 150 1879. 

 Streptorhynchus tenuis, Hall, llth Geol. Rep. of Ind., p. 287 1881. 



Shells found at Waldron, large ; those found in the rocks near Louisville of 

 medium size; semi-circular or broadly semi-elliptical; cardinal line less than 

 greatest width of shell ; cardinal extremities rounded. 



Ventral valve moderately convex at the umbo and the umbonal region, extend- 

 ing over about one-third of the whole surface of the valve ; balance slightly 

 concave ; cardinal area narrow, but increasing in height at the beak and near 

 it ; beak elevated and straight ; triangular fissure of moderate size and closed 

 by a deltidium. 



Dorsal valve moderately convex ; umbo very small ; surface depressed near 

 the cardinal extremities, and also near front margin. 



Surface ornamented with radiating striae of -different size, all fine and 

 rounded, but alternately large and small, which are strongly curved on the 

 lateral portion of shell. These radii are crossed by fine concentric striae, which 

 give surface of shell, under lens, a beautiful rugose character. The substance 

 of the shell is very thin. Large specimens of this species are found at Wal- 

 dron, Indiana, of which one individual, according to Prof. Hall's statement, 

 measures forty millimeters in length, by fifty millimeters in width. The speci- 

 men before me being the only one found in our rocks, measures nine lines in 

 length by fourteen lines in width. 



Formation and Locality. Found in the Niagara limestone at Waldron, Indiana, and in the quar- 

 ries east of the city of Louisville, Ky. It is very rare ; only few specimens are so far found at Waldron, 

 and but one at Louisville j this last one belongs to my collection. 



Genus Strophodonta. Han. 



Strophodonta, Hall. Pal. 1ST. T., Vol. 2, p. 631852. 

 Etymology : strophos, bent ; odous, tooth. 



Shell with general form and characters of Leptaena; one valve convex, the 

 other one concave ; the concave one following the general curve of the other, 

 and being nearly parallel with the same. Cardinal area continuous, nearly 

 linear, mostly occupied by the dorsal valve, striated transversely; foramen 

 decidedly closed ; ventral valve with the hinge-line uninterrupted ; margins of 

 the hinge-line crenulated ; area strongly striated in the transverse, and more 

 slightly in the longitudinal direction. Muscular impressions somewhat bilat- 

 eral. 



The crenulated hinge-line is a very strong distinctive character, since in 



