Eastman: Dipterus Remains from Colorado. 281 



in the Catskill of Pennsyhania, and the nearer affinities of B. colo- 

 radensis appear to be with certain Scottish Old Red Sandstone forms. 



Only a few of the remains collected by Messrs. Spurr and Tower 

 from the fish-bearing locality at Aspen, in central Colorado, have come 

 under the writer's inspection. It seems to be certain, however, that 

 Arthrodiran fragments and teeth of Holoptychius or some allied 

 Crossopterygian occur, and the presence of Dipnoans was suspected 

 on account of "certain smooth scales displaying their characteristic 

 perforations." Concerning these latter it was remarked by the writer 

 in 1904 that the remains "are noteworthy for furnishing the only 

 indication we possess at present of the occurrence of Lung-fishes in 

 the Colorado Devonian." No evidence had at that date been ob- 

 tained which might suggest a relationship between the fauna of the 

 Colorado Devonian and that of the west central states, and the 

 absence of Ptyctodont tritors and Dipnoan teeth, such as constitute a 

 so well-marked feature of the Upper Devonian of Iowa, was regarded 

 as somewhat surprising. 



Owing to the insufficient evidence on the paleontological side, it 

 was impossible in 1904 for Dr. Cross or the present writer to reach 

 altogether satisfactory conclusions as regards the stratigraphic 

 equivalence of the Colorado Devonian. The former writes in his 

 article already referred to for that year: 



"While certain correlations for both the Elbert and Ouray forma- 

 tions seem definitely indicated by present knowledge, meagre as it is 

 in some directions, there is a marked contrast between the lower 

 Palaeozoic section of western Colorado and that of the Front range, 

 especially as exhibited near Canyon City." 



Likewise Eastman, at the close of his article accompanying that of 

 Dr. Cross: 



"For the present, the question as to the origin of the vertebrate 

 fauna of the Colorado Devonian must be considered as problematical, 

 and one which will require considerable further evidence and investi- 

 gation before it can be answered satisfactorily. It is evident that the 

 remains thus far obtained . . . open up problems of distribution, 

 and others of a geological nature, which are worthy of careful study." 



Thus the problem stood eleven years ago. Thanks to the con- 

 tinued interest and activity of Dr. Cross, valuable new^ information 

 has recently been acquired which bears upon the homotaxial relations 



