THE 



AMERICAN JOURNALOFSCIENCE 



[F OURTH SERIE S.] 



Art. XXYIII. — A New Devonian Formation in Colorado / 

 by Whitman Cross. 



The existence of Devonian formations in the San Juan 

 reo-ion of Colorado Avas first established through the discovery 

 of invertebrate fossils by F. M. Endlich of the Hayden Survey, 

 during the summer of 18 74.* The Devonian character of the 

 fauna discovered by Endlich was announced by F. B. Meek,f 

 later questioned by C. A. "White % and K. P. Whitfield,§ reaf- 

 firmed by C. Schuchertj** and finally established by G. H. 

 Girty -ft upon the basis of extensive collections from many 

 localities obtained during the survey of the San Juan country 

 under the direction of the writer. The limestone formation, 

 from which Endlich collected a few fossils and which has 

 yielded the extensive fauna studied by Girty, was described by 

 A. C. Spencer,^ at the time the writer's assistant in the Colo- 

 rado work, as the Ouray Limestone. It has been found, since 

 the cited publications by Spencer and Girty, that the upper 

 part of the lithologic unit, the Ouray limestone, contains a 

 Mississippian Carboniferous fauna. This has now been de- 

 scribed by Girty, ^§ in his review of the known Carboniferous 



* Ann. Rep. U. S. Geol. and Geog. Survey, etc., for 1874, pp. 211-214. 

 •f Bull. U. S. Geol. and Geog. Survey, etc., 2d Ser., No. 1, 1875, p. 46. 

 % Bull. U. S. Geol. and Geog. Survey, Terr., 2d Ser., No. 1., 1875, p. 47. 

 g U. S. Geol. Survey. Monog. XII, 1886, p. 56. 

 **Bull. U. S. Geol. Survey, No. 87, p. 166. 



ff Devonian fossils from Colorado. The Fauna of the Ouray Limestone. 

 U. S. Geol. Survey, 20th Ann. Eep., Pt. II, 1900, pp. 25-81. 



XX "Devonian Strata in Colorado." this Journal (4), ix, 1900, p. 125. 

 §§ " The Carboniferous Formations and Faunas of Colorado ;" Profession. 

 Paper No. 16. U. S. Geol. Survey, 1903. 



Am. Jour. Scl— Fourth Series, Vol. XV1I1, No. 106.— October, 1904. 

 17 



