0. R. Eastman — Upper Devonian Fish Remains. 253 



Art. XXIX. — On Upper Devonian Fish Remains from 

 Colorado ;* by C. R. Eastman. 



Through the courtesy of Drs. Whitman Cross and T. W. 

 Stanton, of the United States Geological Survey, a number of 

 Paleozoic fish remains from Colorado have recently been 

 placed in the hands of the writer for investigation. The 

 greater number of these were collected by Dr. Cross in the 

 San Juan region, while engaged on the survey of the Durango, 

 Engineer Mountain, and Needle Mountains quadrangles. A 

 few detached plates and scales from Aspen, collected some 

 years ago by J. E. Spurr, complete the collection. The 

 character of the remains is indicative of an Upper Devonian 

 horizon for all the localities, and in the case of at least two of 

 them, an Upper Devonian invertebrate fauna has been found 

 in beds overlying the fish-bearing strata. For an interesting 

 account of the stratigraphy of the region, the reader is referred 

 to the preceding paper by Dr. Cross, wherein the name of 

 Elbert formation is proposed for the fish-bearing beds. In the 

 present article it will be sufficient to point out the general 

 nature of the vertebrate fauna, and to inquire into its relations 

 with other Devonian assemblages. The several localities may 

 be considered in the following order. 



Durango Quadrangle. 

 The specimens from the Elbert formation of Rock wood 

 being of exceptional interest, the details of their occurrence 

 may be noted rather fully. They are all from a single slab of 

 quartzite found in the talus at the base of a cliff about one 

 mile south of Rockwood. It is stated by Dr. Cross in memo- 

 randa accompanying these specimens that their probable source, 

 as indicated by lithological evidence, is " at least 100 feet above 

 the basal conglomerate, which here rests upon granite. Above 

 the quartzite ledge, with a small covered interval, comes the 

 Ouray limestone, containing a Devonian invertebrate fauna. 

 The variable quartzite series below the limestone in the 

 Animas Valley never exceed 300 feet in thickness, and have 

 yielded no other forms, though carefully searched for a num- 

 ber of miles along the outcrop. . . . The occurrence of fish 

 remains in the Silurian at Canyon City, as described by Wal- 

 cott, suggests that these fish remains from near Rockwood 

 belong to Silurian beds intermediate between the Cambrian 

 and the Devonian. Very careful search did not suffice to 

 detect the layer from which the slab in question came." In a 



* Published by permission of the Director of the United States Geological 

 Survey. 



