gS BuLi^ETiN 12 226 



RELATIONS OF THE FAUNAS. 



RocKFORD Limestone Fauna. 



The fauna of the Rockford limestone is quite unlike eithei" the 

 fauna above or below it in the Indiana sec?tions, although its af- 

 finities are distincftly Carboniferous. A stud}' of the species re- 

 corded from the Rockford fauna in Part III shows that seventeen 

 species, or more than one third of the total number reported in it, 

 belong to the Cephalopoda. Nearly all of the species of this 

 fauna have been described from Rockford, and very few of these 

 have been reported from other horizons or localities. 



The only species of Protozoa recorded from this fauna is also 

 reported by Keyes from the Kinderhook of Missouri. 



Of the two corals only one is known elsewhere, and this one is 

 reported doubtfully from just above the Black shale in Tennessee 

 and the Waverly in Ohio. 



Of the four Brachiopods which have been positively identified 

 in this fauna one is known from the Kinderhook and one from 

 the Waverly outside of the state, while the other two are un- 

 known outside of the Rockford limestone. Not one of these four 

 has been identified in the faunas above or below the Rockford 

 limestone. The presence in the fauna of a Leiorhynchus , which 

 is probably L. quadicostatus and Ambocc^lia gregaria, affords the 

 only trace of Devonian affinities observed in the fauna. 



Nine Gastropods have been recorded from the Rockford lime- 

 stone, none of which are known in the other faunas of the Indi- 

 ana and Kentucjky sedlions. 



The Cephalopods are represented by seventeen species, all of 

 which, so far as known, are limited in Indiana and Kentucky to 

 this fauna. 



Only two species of Trilobites have been described from the 

 Rockford fauna, one of which, Proetus doris, has been identified 

 by Herrick in the Ohio Waverly. 



The unique charadler of the Rockford limestone fauna, fur- 

 nishing as it does so many species not known in other faunas, 

 seems to fully justify its separation from the faunas above and its 



