GIRTY, THE WEWOKA FOItMATIOX OF OKLAHOMA 129 



C. mesolobus var. decipiens is very abundant in the Wewoka forma- 

 tion. It is also abundant in some of the earlier Pennsylvania!! deposits 

 of the Kansas section at about the horizon of the Parsons formation. 



In the literature, no citation can definitely be included in the synonymy 

 except my own identifications of specimens obtained in Oklahoma and 

 in Colorado. I remarked in that connection that the Colorado specimens 

 were characteristic in every way, but I had for comparison not typical, 

 striated C. mesolobus, but specimens of the present variety. 



Horizon and locality: Wewoka formation; Wewoka quadrangle, Coal- 

 gate quadrangle, Okla. 



Chonetes mesolobus var. euampygus var. nov. 



Considerable variation is shown by shells of the mesolobus group in the 

 strength with which the characteristic lobation is developed. In some of the 

 larger individuals especially, it can hardly be distinguished at all, and when, 

 as is usually (?) the case, such specimens belong to the smooth or decipiens 

 type, they simulate C. geinitsianus very closely. It is at least possible that 

 C. geinitzianus may have had this derivation, though one would have said ff 

 priori that such phytogeny was of all the least probable. 



It is probably true as a general statement, though not without exceptions, 

 that the strength of the lobation varies inversely as the size of the individual. 

 There is at all events a group of shells which stand out strongly and distinctly 

 by reason of their small size and deep lobation. That they are mature shells 

 is indicated by their strong convexity and by the fact that young individuals 

 of the larger form would be more faintly lobed. Though they intergrade with 

 the larger, less strongly lobate shells through larger examples which have an 

 almost equal strength of lobation, they form a distinct, and as a rule an 

 easily discriminated group which sometimes occurs alone to the exclusion of 

 the typical variety. In sculpture, these shells seem to be allied to the variety 

 decipiens. They are usually unstriated, but show traces of stria? more fre- 

 quently than decipiens. Seldom, if ever, is the striation as strong as in well- 

 characterized specimens of C. mesolobus s. s. 



None of the specimens referred here exceeds 10 mm. in width, and the average 

 is nearer 7 mm. 



Horizon and locality : Wewoka formation ; Wewoka quadrangle, Coal- 

 gate quadrangle, Okla. 



Productus insinuatus sp. nov. 



1892. Productus wquicostatus. Hall and Clarke. Geol. Surv. New York. Pal., 

 vol. 8, pt. 1, pi. IT A. figs. 22. 2::. 



Coal Measures: Nebraska. 

 1892. Productus wquicostatus. Hall and Clarke, State Geologist New York. 



. Eleventh Ann. Rept.. for 1891, pi. 22, figs. 11, 12. 



Coal Measures: Nebraska. 



