41() AXXALS OF THE CaRNKGIE MuSEUM. 



about fifteen miles south of here, at Zeigler's Canon of the Bighole 

 River, a most beautiful section sup])lements that on Camj) Creek. 

 The first-named one begins with the Archcxan and ends with the 

 massive Carboniferous limestone, while the section at Zeigler's Canon 

 begins with the upper Carboniferous quartzytes and goes through 

 Permian ?, and a thick series of Mesozoic rocks, probably to the 

 Tertiary. 



CAMBRIAN AND DEVONIAN. 



Regarding these formations I cannot add much to what has already 

 been published. The Cambrian, though it varies locally, appears to be 

 more nearly uniform lithologically than the formations extending up- 

 ward from the Carboniferous. In an outcrop on the crest of the Ruby 

 Mountains it contains many Trilobitc heads, as it does on the Gallatin 

 near Logan. At the foot of these mountains farther to the south, in a 

 glauconitic sandstone, I found some Trilohite remains which S. A. 

 Miller identified as AsapJiisciis whecleri. What has the appearance 

 of Cambrian limestone occupies a small exposure in the Algonkian 

 area south of Missoula, on the Bitter Root River, opposite Lo Lo 

 Creek. 



The Devonian shales, about three or four miles northwest of Three 

 Forks, are fossiliferous and contain finely preserved Brachio]:)ods and 

 Cephaloi)ods. Mr. George H. Girty identified a small collection sent 

 to him. The following is the list : 



Spirifcr disjiinctus. 



Cleioihyris n. sp. 



Camafottvchia Tethys. 



Fugnax piigmis. 



Goniatiies (2 sp.). 



The shales on Camp Creek contain a few fossils. 



CARBONIFEROUS. 



The Carboniferous here is well worthy of a careful study. The 

 lithological characters, especially in the upper portion, are not so uni- 

 form as we might expect in marine formations. 



Bridgcr Mountains. — The rocks of the Bridger Mountains have been 

 mapped in the Three Forks Folio. On Bridger Peak, in the Madison 

 limestone, I found the following new si)ecies which were named and 

 described by S. A. Miller: " 



5 Bulletins 10 and 12 of the Illinois State Museum. 



