FOSSILS OF THE SILURIAN AND DEVONIAN ROCKS. Ill 



fer of the Coal Measures. Conrad's first description of this species and its naming date only back to 1842. 

 Mr. Morton's right to the name can not be disputed; Mr. Conrad's species must, therefore, be dropped. 

 Mr. Miller has proposed the name " Conradana " as a substitute, which I hereby cheerfully accept. Mr. 

 Miller named the species in honor of Mr. Conrad, former geologist of the State of New York. 



Spirifera crispa, var. simplex. HALL. 



Plate XVII., figures 36 and 37. 

 Spirifera crispa, var. simplex, Hall, llth Eep. of Ind. 1881. 



Shell small, semi-circular or semi-elliptical, more or less gibbous or ventri- 

 cose; both valves about equally convex ; hinge-line somewhat less than the 

 greatest width of the shell ; cardinal extremities obtuse or rounded. Surface 

 plicate. 



Central valve ventricose, with its greatest convexity about the middle of 

 the valve, from where it curves regularly towards the anterior and lateral 

 margins ; mesial sinus well defined from apex to front, deep and angular in 

 the bottom, and widening towards the front, where it forms a strong triangular 

 projection ; cardinal area high, but not defined in its margins, which are 

 rounded, and gradually extend into the surface of the valve ; foramen or fis- 

 sure long and narrow ; beak arched, but not incurved. 



Dorsal valve nearly as ventricose as the other, having its greatest convexity 

 about the middle of the valve, from where it curves regularly towards front 

 and sides. Mesial fold well defined, strong and angular ; beak small and curv- 

 ing over a linear area. 



Surface marked on each side of mesial depression and elevation by two or 

 three plications, of which only the first one near fold or sinus is mostly strong 

 and well marked, while the others are either only slightly elevated or some- 

 times entirely obsolete. The whole surface of the shell is covered by strong, 

 thread-like concentric striae. 



These specimens are considerably smaller than those used by Professor Hall 

 for his figures and description in the Indiana Report, which came from Wal- 

 dron, Indiana. Even some slight differences exist between our Kentucky 

 shells and those from Indiana, but these differences do not justify a further 

 specific separation. 



Formation and. Locality. Occurs in the upper strata of the Niagara formation, in the quarries 

 east of the city of Louisville, Ky., where it is somewhat abundant, but well preserved specimens are rather 

 rare. 



