MINGLING OF CARBON J FERGUS SPECIES. 89 



tical with species found in the Mississippi Valley in Lower Carboniferous 

 rocks, while many of them have usually been considered as restricted to 

 that horizon. Associated with them, in sufficient force to sho\v ;i comming- 

 ling of types, occur characteristic Coal-measure fossils like Athyrix subtilita 

 and Euomphalus subrugosus. Mingled with these fossils, in the same strata, 

 are the Lamellibranchiates, which present so striking a feature of the Carbon- 

 iferous fauna. Notwithstanding the fact that the Devonian, at Eureka, 

 furnishes an exceptionally rich fauna in Lamellibranchiates, nearly all the 

 species found in the Carboniferous occur for the first time at this horizon, 

 and but few, if any, specifically agree with the Devonian forms. This is all 

 the more noticeable because species, which are identical with those found 

 in New York and Ohio, are in the latter localities only recognized in restricted 

 areas x and inmost instances from horizons low down in the Devonian. This 

 is well shown by the species Grammysia arcuata and Macrodon hamiltonte, 

 both regarded as typical of the Hamilton group, while others like Sanguino- 

 lites ceolus is referred to the Chemung and to the Waverly sandstone of 

 Ohio. 



The complete list of species from these strata is as follows : 



Archseocidaris, sp. f Aviculopecten, sp. ! 



Fenestella (3 sp. !) Myalina nessus. 



Discina newberryi. Pterinopecten hoosacensis. 



Streptorhynchus crenistria. Pterinopecten spio. 



Grthis resupinata. Crenipecten hallanus. 



Chonetes grannlifera. Ptychopteria protoformis. 



Chonetes verneuiliana. Pinna consimilis. 



Productus prattenianus. Pinna inexpectans. 



Productus semireticulatus. Modiomorpha ambigua. 



Spirifera camerata. Modioiuorpha ! desiderata. 



Spirifera neglecta. Nucula insularis. 



Spiriferina kentuckiensis. Nucula, sp. ? 



Athyris subtilita ? Solenomya curta. 



Ehynchonella eurekensis. Macrodon truucatus. 



Rhynchonella (Leiorhynchus type). Grainmysia arcuata. 



Aviculopecteu affinis. Grammysia liannibaleiisis. 



Aviculopecten eurekensis. Edinondia medoii. 



Aviculopecten haguei. Sanguinolites a?olus. 



Aviculopecten peroccidens. Sanguinolit's a'olus. var. 



