The ISTew Species of Brachiopoda. 34:7 



greatest diameter of the valves. Cardinal area of the pedicle- 

 val^e high, sometimes regularly triangular, often distorted or 

 somewhat incurved ; deltidium broad at the base and rapidly 

 tapering with a faint median groove on its surface. Pedicle- 

 valve convex in the umbonal region, irregularly rugose and 

 depressed over the pallial area. Brachial valve very gibbous at 

 the umbo, the greatest convexity being behind the center of the 

 valve. From the umbonal region the surface slopes evenly toward 

 the lateral and anterior margins, but is more abruptly depressed 

 toward the cardinal extremities where it forms short subalate 

 expansions. The valve is but slightly unsymmetrical and is 

 bilobed by a conspicuous median sinus which takes its origin near 

 the umbo, and widens to the anterior margin. 



Surface covered by fine radiating striaB which are of subequal 

 size over the umbonal region, but toward the margin became 

 arranged in fascicles on account of the addition of finer striae as 

 growth advances. Concentric rugae and growth- varices are fre- 

 quent, especially on the pedicle- valve. 



Upper Coal Measures. Near Kansas City, Missouri. 



Derbya Bennetti. 



Plates, figs. 3-8. 



Deri ya Bennetti B.a\\. Palaeontology of N, Y., vol. VII [, pt. 1, p. 348, pi. 

 xi a, figs. 34-39. 1892. 



Shell subtrihedral in general aspect, quite irregular in its 

 groTvth. Hihge-line short, its extremities on both valves being 

 auriculate. Pedicle valve much the. more irregular in growth, 

 sometimes retaining the scar of attachment at its apex. Cardinal 

 area unusually high, narrow, erect or slightly incurved, and 

 frequently distorted ; delthyrium curved. General surface of the 

 valve depressed-convex in the middle, sometimes rapidly sloping 

 in all directions, at others concave in the umbonal region; as a 

 rule very unsymmetrical. The brachial valve is deep, more regu- 

 larly convex and has a full rounded umbo and a conspicuous 

 median sinus. On the interior the pedicle valve bears an 

 extremely high median septum which is united with the dental 

 ridges near the apex. The cardinal process is high, erect and 

 deeply bilobed, each of its apophyses being strongly grooved on 

 its posterior face. Other internal characters unknown. 



