A CARBONIFEROUS BRACHIOPOD 655 



express his deep gratitude for their aid and assistance. The photo- 

 graphs for the plates were also made by Professor Cumings. 



Owen's type specimen of C. granulifer came from the Carbon- 

 iferous limestone, near the mouth of Keg Creek, lowa.^ This locality 

 has never been definitely correlated with the Kansas section, but as 

 near as can be made out from Meek's discussion of the rocks of the 

 Missouri River section^ and Owen's description^ of the locality from 

 which the type specimens were taken, as correlated by Beede and 

 Prosser,'^ it appears to come from some horizon between the Topeka 

 and the Tecumseh limestones, probably nearer the Deer Creek lime- 

 stone than any other. The material which the writer used, contained 

 specimens covering practically the entire range of the species, 

 including the equivalent of the horizon from which the types were 

 taken. 



SPECIFIC CHARACTERS 



Mature form. — Shell semi-circular in outHne, having the greatest 

 breadth at the hinge-line, with cardinal angles somewhat attenuate. 

 The size of the shell varies greatly. Size of largest specimen, t,t, mm 

 in width by 19 mm in length. Average size of adult, 28 mm in width 

 by 15 mm in length. The shape also varies in that the cardinal 

 angles of some specimens are much more mucronate than in others 

 (Plate I) and in some specimens there is a tendency to develop a 

 mesial sinus in the ventral valve. Both of these characters are seen 

 in Plate I, rows 3, 4. 



Dorsal valve. — In the Grand Summit specimens (the most per- 

 fectly preserved in the lot) the dorsal valve is concave to the extent of 

 two or three mm. This valve is ornamented with radiating striae and 

 concentric Hnes of growth around the margin. The striae number 

 about fifty near the beak but at the frontal margin increase to about 

 one hundred and fifty by implantation. The shell is punctate in the 

 furrows between the striae. The striae become obscure on approach - 



1 Owen, Geol. Rep. Wis., Iowa, and Minn., p. 583. 



2 Meek, U. S. Geol. Surv. Nebr. 



3 Owen, Geol. ReP. Wis., Iowa, and Minn. 



4 Prosser, "Comparison of the Carb. and Penn. Form, of Neb. and Kans.," 

 Tour. Geol., Vol. V, pp. 1-16, 148-72. 



