104 PALAEONTOLOGY OF KENTUCKY. 



depressed towards base ; the greatest convexity a little above middle of valve. 

 The hinge-line is about one-third and sometimes one-half as long as width of 

 shell. Surface usually smooth or very finely papillose ; but in perfect speci- 

 mens the surface is covered by numerous fine setae, which are matted together, 

 and the interstices being filled with clay, it has a rough appearance while 

 under a lens; these setae give a finely striate aspect. Beneath the fine papillose 

 surface the texture of the shell is minutely punctate. 



Formation and Locality. Found occasionally in the Corniferous limestone at and around the Falls 

 of the Ohio, in Kentucky and Indiana. It is a rather rare shell. 



Nucleospira elegans. HALL. 



Nucleospira elegans, Hall. Pal. N. Y., Vol. III., p. 2221859. 



Shell sub-orbicular, wider than long. Lateral margins strongly curved, baso- 

 lateral margins very slightly curved, almost straight. Central third of the 

 base somewhat prolonged or produced, and straight. Ventral valve moderately 

 convex, except in the umbonal region, which is somewhat gibbous. There is 

 sometimes, on the elevated center, a flattened or faintly depressed mesial line 

 from umbo to base ; beak elevated above that of the opposite valve and closely 

 incurved upon it. Area usually covered by the incurved beak, but sometimes 

 visible. Dorsal valve depressed convex, but sometimes almost as convex as the 

 ventral ; more elevated in the umbonal region ; beak small, strongly incurved 

 beneath the beak of the opposite valve. Surface of the shell finely and beau- 

 tifully punctate, and sometimes preserving remains of its former pilose cover- 

 ing. Some specimens of this species, showing the cardinal area, might be 

 mistaken for Orthis. 



Formation and Locality. Occurs in the Niagara limestone east of the city of Louisville. A large 

 specimen measures eight lines in width by seven in length, while a smaller one has a width of six lines by 

 a length of five. 



Nucleospira pisiformis. HALL. 



Plate XXXIII., figures 7, 8 and 9. 

 Orthis pisum, Hall. Pal. N. Y., Vol. II., p. 2501852. 

 Nucleospira pisiformis, Hall. Pal. N. Y., Vol. III. 1859. 

 Nucleospira pisiformis, Hall. Trans. Alb. Inst., Vol. IV., p. 226 1863. 

 Nucleospira pisiformis, Hall. 28th Regent's Rep., p. 160 1879. 

 Nucleospira pisiformis, Hall, llth Geol. Rep. of Ind., p. 302 1881. 



Shell small, sub-globose ; valve nearly equal, each valve with as light de- 

 pression down the center. Ventral valve somewhat more convex, and beak 

 more elevated than in the dorsal. Area narrow, small, scarcely extending 



