148 UNIVERSITY OF COLORADO STUDIES 



In middle or upper Mesa Verde strata three miles south of Axial. 



Ostrea subtrigonalis E. and S. Corbicula occidentalis M. and H. 



Anomia micronema Meek Corbicula cytherijormis M. and H. 



In the upper Mesa Verde, below the upper coal vein, about one mile 

 north of W. B. Blythe's house, on the north side of White River four 

 miles west of Meeker. 



Ostrea subtrigonalis E. and S. Corbicula planumbona Meek 



Modiola regularis White Legumen ? sp. 



Corbicula occidentalis M. and H. Turritella sp. 

 Corbicula cytherijormis M. and H. 



The Mancos faunas are strictly marine, that of the lower part being 

 the fauna which elsewhere marks the Colorado group (Benton and 

 Niobrara). The lowest Mesa Verde fauna at Rifle Gap is also marine, 

 characteristic of the Montana group (Pierre and Fox Hills), the chief 

 species being Cardium and Mactra. The next higher fauna (at Rifle 

 Gap) includes Anomia rcetiformis, which at the type locality east of the 

 Front Range is found associated with marine species, but may also have 

 inhabited brackish water, as its relative, A. micronema, probably did. 

 Ostrea subtrigonalis may be both marine and brackish-water, and 

 Corbicula occidentalis is considered a brackish-water form. Above the 

 latter horizon the Mesa Verde faunas are decidedly brackish-water. 



It will be noticed that with the exception of the very lowest fauna of 

 the Mesa Verde and one species in next to the lowest, the fossils we 

 found in that formation are species which in eastern Colorado occur in 

 the Laramie, but the finding of marine Lewis shales between the Mesa 

 Verde and the Laramie in the Yampa region indicates that the beds are 

 not assignable to the Laramie. 



The Corbicula horizon north of Blythe's house is about 200 to 300 

 feet (estimated) below the lower plant horizon east of his house, which 

 latter is discussed by Professor Cockerell in a subsequent part of the 

 present report. The lower plant horizon is perhaps 300 or 400 feet 

 below the upper plant horizon northwest of the house. Both of these 

 plant horizons occur above the highest coal vein noted by us in that 

 locality, and contain fossil leaves in great abundance, the lower one 



