BEEDE AND ROGERS.| Coal Measures Faunal Studies. 833 
Fig. 3. Cottonwood limestone at Beaumont, in three layers, with 
over and underlying shales. Part of Plate XLIII. 
are the ophiuroids (rare) ; the culmination of Productus ne- 
braskensis Owen, nearly a thousand specimens of which are in 
our collection from a single stratum at Grand Summit; the 
abundance of an undetermined species of Schizodus and the 
culmination of Thamniscus octonarius Ulrich, which is present 
in thousands at Beaumont. The pelecypod and gastropod ele- 
ments in this faunule are very strong in this region, as are the 
octracods. Derbya multistriata (Meek) becomes very abun- 
dant for the first time, and there is almost a total absence of 
Seminula argentea Mort., Chonetes granulifer Owen, and Pro- 
ductus nebraskensis Owen, which make up a very large per- 
centage of this fauna in the northern region. 
Faunal Divisions. 
The study of the faunal characteristics of the Kansas Coal 
Measures has given rise to certain unexpected questions of 
nomenclature in a larger way, and the results are hardly in ac- 
cord with the general impressions of the subject. 
The division of the rocks into two groups, characterized 
by both faunal and economic features, hardly fits the Kan- 
sas conditions. They fall rather into four divisions which are 
