d40 EXPLORATIONS ACROSS THE GREAT BASIN OF UTAH. 



the Hamilton group of the New York series, that, when taken in connection with the 

 lithologica] characters of the matrix, they leave a strong impression on the mind that 

 they probably belong to about the same horizon. 



The fossils found at the other localities mentioned above are, I think, decidedly 

 Devonian types, and also occur in dark-bluish limestone. They consist of Atrypa aspcra, 

 or a closely allied species, A. reticularis, a small Products, and three or four new species 

 of Spirifer. As the genus Produdus is now generally regarded as not dating back 

 farther than the Devonian system, and neither Atn/pa rdiadarh nor A. aspera ranges 

 up into the Carboniferous, while the species of Spirifer, as well as the small Produdus 

 associated with these, are all closely allied to forms characterizing the Hamilton group, 

 the evidence is nearly or quite conclusive that the rock from which these fossils were 

 obtained belongs to the Devonian system, and I think it will be found to be nearly on 



It is an interesting fact, in case these specimens should really prove to be of the 

 age of the Hamilton series, that at this distant locality thev should be found in beds 

 having almost exactly the litl.ological characters of some of the dark calcareous por- 

 tions of that formation in New York; while the fossils of the same age found in the 

 intermediate Western States, generally occur in much lighter-colored strata. 



It is worthy of note that the localities at winch these specimens were obtained are 

 near twelve hundred miles farther westward than such fossils June hitherto been found in 

 .situ, so far as known to the writer, within the Territory of the United States. It is true 

 that a few fossils, consisting of some IJmclthpoda, and others similar to Ibnmtis, collected 

 by Captain Stansbury from slu.ly arenaceous beds near the North Platte, three or four 

 days' march beyond Fort Laramie, were formerly supposed to be of Devonian age;* 

 but it is now known that the outcrop there alluded to consists of Jurassic,. and probably 

 some Triassic, strata; though the fossils were obtained from the former.' 



Some specimens belonging to the genera Spirifer, Couoeardium, &c., collected by 



west), were supposed by Dr. Shumard to be also of Devonian age, hut the evidence 

 was not regarded as conclusive, and the fossils were found in an erratic mass, the exact 

 original position of which could not be determined. 



collected west of Lake Utah, near Camp Floyd, latitude ZZ/lZth^l^Z 

 112° 8' west; and at two or three localities much farther westward, near Humboldt 

 Mountains, already referred to. Those from the first of these localities occur in a hard 

 compact, dark-colored siliceous limestone, which I am informed by Mr. Kii-elmann is 

 rather extensively developed in that region. They are all silicified and not in a con- 

 dition to show very satisfactorily their specific characters, though forms very similar 

 to Orthis MichUini and He/uiprouites creuistria occur among them. There are also 

 along with these, fragments of Corals, Spirifer, Athyris, and the spiral axis of a species 

 of Archimedipora. As the last-mentioned fossil belong to a -vnus common in tho 



Lower Carboniferous, and not vet certainly known to ran«-e up into the 



ures, and the forms associated with it resemble species occurring in the Lowe 



ries of the West, while there is an absence of any exclusively Co 



* See Captain Stansbury's Report, Great Salt Lake, page 403. 



-M,;> 



