40-1 DRAKE— THE GEOLOGY OF INDIAN TERKITORY. [Sept. 3, 



assigned by Waagen to liis genus Margin ifera, although Hall and 

 Clarke have recently shown, in "Nat. History of New York," 

 FalcBotiiology, Vol. viii, '' Brachiopoda," p. 331, that the genus is 

 not valid, and can have at most subgeneric value. As such it is 

 here retained. 



Occurrence and Horizon. — Boone limestone (Burlington-Keo- 

 kuk), three miles southeast of Westville ; Boone limestone, seven 

 miles east of Adair, PI. IX, Fig. 2 ; Boston group (St. Louis- 

 Chester), five miles east of Adair, PI. IX, Figs, i and 3. About 

 fifteen specimens collected, altogether. 



Froductus cherokeeensis nov. sp. Drake. PI. IX, Figs. 4 and 5. 



This species resembles closely P. seinireticulatus Martin, but is 

 always smaller, more compressed laterally, more highly arched, 

 and has the mesial sinus more pronounced. It is nearest akin to 

 P. inflatus McChesney, but the umbo is not so prominent, nor so 

 greatly incurved as in P. inflatus ; also the ribs seem a little coarser 

 on P. cherokeeensis. 



The dorsal valve is strongly concave, the ventral is very convex, 

 with strong medial sinus. The surface of both valves is ornamented 

 with distinct ribs, often dichotomous ; the region near the beak is 

 distinctly reticulated by the growth lines. There are occasional 

 spines on the surface. 



The ears are somewhat more extended than on P. seniireiiculafuSf 

 but the total proportional width of the shell is less than on that 

 species. 



Occurrence and Horizon. — Rather common in the Upper Boone 

 limestone (Burlington-Keokuk), West mountain, three miles south- 

 east of Westville ; in the Fayetteville shale (Warsaw), on Grand 

 river, at Adair's ferry; in the Boston group (St. Louis-Chester), 

 eight miles southeast of Big Cabin, and in the same horizon a half 

 miles south of Vinita ; in the Boston group, five miles southeast of 

 Adair, PL IX, Figs. 4 and 5. The species is confined entirely to 

 the Lower Carboniferous in Indian Territory, and a very similar 

 form has been found in the Fayetteville shale (Warsaw) of Arkan- 

 sas, and also in the Marshall shale, probably St. Louis, of that 

 State. It is worthwhile to separate this species from P, semireticu- 

 laius from its stratigraphic importance, and because of the unlike- 

 ness of the two and the difference of their associated faunas. 



Pro ductus pert e7iuis Meek. PI. IX, Figs. 8-10. 



