MINGLING OF CAKBONIFEEOUS SPECIES. 89 



tical with species I'ouiul in the Mississijjpi Aalle}' in Lower Carbonit'erous 

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

 that horizon. Associated with them, in sufficient force to show a comming- 

 ling of types, occur characteristic Coal-measure fossils like Atkyris sitbtilita 

 and Euomphuluti suhniijosus. Mingled with these ft>ssils, 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 and in most instances from horizons low down in the Devonian. This 

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

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

 lites reoliis 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. ? Aviciilopecten, .sp. ? 



Feuestella (.'3 sp. ?) Myalina ut'ssus. 



Disciua newberryi. Pteriuopecteu hoosaceu.sis. 



Streptorhynchus creiii.stria. Pteriuopecteu spio. 



Orthi-s resupinata. Crenipecten hallanus. 



Chonetes jjranulifera. Ptychopteria protoforinis. 



Clionetes veiiieiiiliaua. Pinna cousiiiiilis. 



Produi'tus pratti'uianus. ^ Pinna inexi)e('tans. 



Productiis semireticnlatus. Moiliomoi-]»lia ambigna. 



Spirifera t-amerata. Modioniorpha ? desiderata. 



Spirifera ueglecta. Nucula iusularis. 



Spiriferiua keutiicliiensis. Nucula, s]). ? 



Athyris subtilita ? Solenoniya curta. 



RhjTichouella eurekensi.s. IMacrodon truucatus. 



Kbyiiclionella (Leiorhyuebus tjiie). Grammysia arcuata. 



Aviculopccten affinis. " Gramniy.sia bannibalensi.s. 



Axnculopecten eurekonsis. Edmoudia medou. 



Avic-ulopeeteu baguei. Sanguiuobtes ii^obis. 



Aviculopeoten peroceideus. Sanguinolites a'obis, var. 



