124 PALEONTOLOGY OF KENTUCKY. 



valve ; beak minute. Mesial sinus well defined, but shallow, and flattened at 

 the bottom, with sub-angular margins rapidly widening towards the front, 

 where it is somewhat produced. 



Dorsal valve depressed, convex, most convex above the middle ; cardinal ex- 

 tremities often inflected ; beak not prominent, incurving over the linear area. 

 Mesial fold well defined and rounded, but flattened on top towards the front. 

 Surface marked by from eighteen to twenty simple rounded plications on each 

 side of the mesial fold and sinus ; only few of these ribs reach to the beak, the 

 others run out on the margins of the cardinal area. 



This species agrees in many points with Prof. Hall's description of Spirifera 

 macronata, in Pal. N. Y., volume 4, page 231, but it differs by its smaller 

 number of ribs, which in this species never exceeds twenty, while macronata 

 has from twenty-five to thirty -five. The area of macronata is straight, while 

 that of mcconathii is always concave, and the surface of this last species is 

 generally smooth, while the surface of the former is covered by several lamel- 

 lose imbricating lines of growth. 



Formation and Locality. Found in the upper strata of the Devonian limestone, at and near the 

 Falls of the Ohio, in Kentucky and Indiana. It is somewhat rare, at least in well preserved specimens. 

 Named after Prof. W. J. McConathy, of Louisville, Ky., who has gathered a very valuable collection of 

 the Devonian and Silurian fauna from the Falls of the Ohio. 



Spirifera marionensis. SHUMARD. 



Spirifer marionensis, Shumard. Geol. Kep. of Mo, p. 203 1855. 

 Spirifer marionensis, Hall. Geol. Rep. of Iowa, p. 511 1858. 



Shell of medium size, nearly semi- circular, moderately gibbous ; length about 

 equal to two-thirds of the greatest width ; valves almost equally convex ; 

 hinge-line longer than greatest width of shell; cardinal extremities pointed, 

 and sometimes mucronate. Ventral valve broadly semi- elliptical or semi- 

 circular, greatest convexity above the middle ; umbo gibbous ; beak pointed 

 and incurved ; sinus well defined, angular and narrow at the beak, becoming 

 broad and shallow below, and marked by two or three dichotomizing plica- 

 tions ; area narrow ; sides nearly parallel and extending to the hinge-extremi- 

 ties, striated transversely ; foramen broadly triangular ; base greater than the 

 height. 



Dorsal valve regularly convex ; flattened towards the cardinal extremities ; 

 mesial elevation very moderate, marked by two or three plications above, 

 which bifurcate below. Surface marked by from twelve to twenty rounded 

 and little elevated plications on each side of the mesial fold and sinus. Plica- 

 tions increasing by bifurcation either near umbo or near base. 



Concentric lines of growth cover the surface, also fine radiating striae, both 

 of which give the shell a granulose appearance. 



