THE RELATIONS. OF SOME CARBONIFEROUS FAUNAS I5 



the case of those of Utah. In Utah an interesting fauna has 

 been found between the Weber quartzite and the " Permo- 

 Carboniferous," characterized by a striking S^rrifo'ina, unique 

 as to size among American representatives of the genus, namely 

 S^iriferina ^ulchra Meek. This species is accompanied by a 

 large Ortholetes^ a large Seminula, a Prodiictus resembling P. 

 ncvadensts, and other forms. This fauna ranges northward into 

 Idaho and westward into Nevada, but is as yet unknown in the 

 southern tier of States. The Capitan fauna is not definitely 

 known anywhere except in the immediate region where it was 

 originally found, and whatever the correlation of the beds of 

 the Utah section may prove to be, there is little prospect of any 

 of them being equivalent to the Capitan. At least their faunas, 

 so far as known, are entirely different. 



The Weber quartzite is underlain by a heavy limestone forma- 

 tion (the Wasatch limestone), the lower part of which is of Mis- 

 sissippian age, the upper being reported as Pennsylvanian. A 

 similar limestone (the Redwall), likewise said to be Mississip- 

 pian below and Pennsylvanian above, lies beneath the Aubrey 

 group in northern Arizona. In southern Arizona a similar con- 

 dition obtains. The lower limestone, which is probably as young 

 as St. Louis in its upper portion but contains no Kaskaskia fauna, 

 is called the Escabrosa limestone,^ the upper one having re- 

 ceived the name of the Naco limestone. The lower part of the 

 Naco is provisionally correlated with the upper part of the Redwall 

 limestone, and will probably prove of Pottsville age. The scanty 

 fauna of the upper Naco appears to correlate it with the Hueco 

 limestone and with the Aubrey formation. So far as known no 

 equivalent of the Escabrosa and lower Naco limestones occurs 

 in the Trans-Pecos region, where even the Devonian found at 

 Bisbee is absent. Thus an unconformity is seen to have pre- 

 ceded the Hueconian beds, evidence of which is quite abundant 

 in the Trans-Pecos region itself. 



The Carboniferous faunas of California, typically shown in 

 Shasta County, have appeared to stand apart from other West- 

 ern faunas. The lower fauna, or that of the Baird shale, is in 

 fact, so far as known, confined to the Pacific slope ; but a better 



' U. S. Geol. Surv., Professional Paper 21, 1904, p. 42, by F. L. Ransome. 



