76 PALEONTOLOGY OF KENTUCKY. 



Rhynchonella gainesi. N. SP. 



Plate XXXI., figures 6, 7, 8, and 9. 



Shell very small; sub- triangular ; length equal to greatest width, which 

 latter is near the base ; the cardino-lateral margins run in almost straight lines 

 from beak to point of greatest width; basal margin broadly curved, nearly 

 straight. Shell concavo-convex, and surface smooth except near the margins, 

 where faint plications are noticed. Ventral valve moderately convex at its 

 umbo, and in its upper one-third ; the balance deeply depressed to a sinus, 

 which occupies the whole width of the valve, and which is margined on each 

 side by the lateral margins of the shell, which deflect here downwards to a 

 sharp prominent point; sinus is flat in the bottom and extends considerably 

 beyond the base, forming a quadrilateral basal extension, which deflects at 

 right-angles upward to tit into a corresponding indentation in the dorsal valve ; 

 the height, measured between the highest point of the basal extension and the 

 apex of the pointed margins of the sinus, is almost equal to the width of the 

 shell ; the beak is elevated and slightly curved. Dorsal valve is somewhat 

 gibbous, with its greatest convexity at the middle of the valve, from where it 

 slopes in strong curves to the cardino-lateral and basal margins ; its central 

 portion runs in a straight line from the beak to the base, forming the mesial 

 fold, which becomes risible at a little above the middle of the valve, and in- 

 creases rapidly to the front or base, where it is very prominent ; umbo is 

 inflated, and the beak incurved into the opposite valve. The surface is en- 

 tirely smooth in its upper half, while the lower one shows some plications, 

 which are plainly visible at the basal margin, but do not extend far into the 

 shell. There are two faint indication, of plications on each side of the mesial 

 fold and sinus, while the mesial fold has three and the sinus two ribs on its 

 summit or bottom respectively. No other surface-markings are observable on 

 account of the silicification of the shell. 



Formation and Locality. Found in the rotten hornstone of the Devonian formation exposed in 

 several washes in Jefferson county, Ky. This pretty little shell is not very rare. This species is named 

 after Prof. J. T. Gaines, of Louisville, Ky., who, as ardent student and collector of fossils, deserves such a 

 recognition. 



Rhynchonella indianensis. HALL. 



Plate XXXIII., figures 18, 19 and 20. 



Rhyn. indianensis, Hall. Trans. Alb. Inst., Vol. IV., p. 2151863. 



Rhyn. indianensis, Hall. 28th Kep. N. Y. St. Mus. Nat. Hist., Mus. edit., p. 163, pi. 26, figs. 12-22 1S76. 

 Rhyn. indianensis, Hall, llth Geol. Rep of Indiana, p. 3061881. 



Shell small, broadly ovate or sub-triangular; length and width nearly equal, 

 or the former is sometimes slightly exceeded by the latter. Cardinal slopes in 



