5 



432 GEOLOGICAL SUEVEY OF THE TEREITOEIES. 



from the cbaracter of the fossils, and the similiaiity of the rock in texture 

 and coiiipositiou to beds to be mentioned below at another locality of 

 the age of the Quebec group, it probably belongs to that horizon. 



Malade City. — The collections from Malade City, iSTorthern Utah, 

 include the genera Camerella, Orthis, UuomjiMlus, Agiiostus, Conocoryplie, 

 Bafhi/iireUus, Bathyurus, AsapliuH., and perhaps Dikeloce2)halus, most of 

 which are common to the Potsdam and Quebec groups; but from the 

 allinities of most of the species and the actual identity of others with 

 Quebec Ibrms, it appears quite clear that these beds belong to that 

 horizon, as stated by Professor Bradley in the Am. Jour, of Science. 

 Two of the species of Unoiitphalits, for instance, seem to be identical 

 with forms described by me some time back among Mr. King's collec- 

 tions from Muddy Creek, Utah, and referred to the horizon of the New 

 York Calcilerous group; generally regarded as representing in part, at 

 least, the Quebec ; while a species of Camerella and one of Orthis seem 

 to be identical with Canadian species of that age. Bathyurus Saffordi, 

 a Canadian Quebec species, is also represented among these collections 

 by specimens agreeing exactly with authentic examples of the same, 

 sent from that horizon in Canada. Several of the other genera are 

 represented by species most nearly allied to Quebec forms. 



Flat-Head Pass. — A few specimens from Flat-Head Pass, Montana, 

 consisting of fragments of Bathyurellus, and perhaps DiJcelocephalus. 

 seem also to be of the same age as the above, judging from the occur- 

 rence among them of Dilxcloceplialus f truncatus, one of the Malade 

 species. 



CARBONIFEROUS AGE. 



Mystic Lalce^ &c. — The fossils from the outlet of Mystic Lake; Caiion, 

 east side of Madison Eiver; Britlger Peak, near Fort Ellis; Black-Tail 

 Deer Creek ; north side Gros Ventres Butte ; Flat-Head Pass ; north 

 side Henry's Lake ; and Caiion west of Gallatin Eiver, (all in Montana,) 

 and Camp 19, Idaho, all evidently came from the same geological forma- 

 tion, a considerable portion of the species being common to several of 

 these localities. They beloug, without exception, to genera that are 

 common both to the Carboniferous and Devonian, while a smaller pro- 

 portion of the genera are also represented even in the Silurian. That 

 these fossils are not of Silurian age, however, is obvious at a glance ; 

 but as most of the species are either new, or, owing to the state of pre- 

 servation of the specimens,* not in a condition to be certainly identified 

 with known forms, almost the only guides we have in determining 

 whether w^should refer them to the Carboniferous or Devonian are the 

 absence of certain genera and the general specific affinities of the entire 

 group of forms. Some of the Prodveti, Choiietes, and Spirifer have 

 rather a Devonian look, while a very finely striated Hemiiyroiiites is very 

 similar to some of the Devonian types of that genus. Even the form 

 I have referred to, H. crenistria, is quite as nearly like some varieties of 

 S. Chemungcnsis {Btrcptorliynclms Chemimgensis, of the 4th vol. Paleont., 

 N. Y.,) from the Chemung and Hamilton groups of the New York 

 Devonian, as it is like the Carboniferous forms of H. crenistria. Ac- 

 cording to Mr. Davidson and others, however, H. crenistria occurs in 

 both the Carboniferous and Devonian of Europe, while the New York 

 form, H. Ghommgensis, differs very little from some varieties of H. cren- 

 istria from the Carboniferous. 



* These collections consist mainly of separate valves of brachiopoids, imbedded in 

 hard limestone. 



