22G GEOLOGI OF THE DENVER BASIN. 



beds in which new fossils are found are necessary to give those fossils value 

 as evidence in geological correlation, especially in the case of allied or 

 adjacent formations. The disregard of this self-evident proposition has 

 already delayed an understanding of some important problems of Rocky 

 Mountain geology, and has caused a great deal of labor in clearing away 

 a confusion which need never have existed. 



EVIDENCE OF INVERTEBRATE FOSSILS. 



'The only invertebrate fossils thus far found in the Denver beds were 

 obtained 1>\ Mr. T. \V. Stanton in L886 from a ravine near the old St. 

 Luke's Hospital, in Highlands, Denver. These were submitted to Dr. C. A. 

 White for determination. I r ivvparus trockiformis and Goniobasis tenuicarinata 

 are the only specifically identifiable forms, while imperfect shells interred 

 to ( Jorbicula, Physa, and Unio are also present. These species of Yiviparus 

 and Groniobasis are common in the Laramie and are also known in the boil 

 Union, and in what Dr. C. A. White lias called the Wasatch Eocene, in 

 Utah. The other forms also possess a wide range, and it is clear that these 

 fossils are without value in the discussion to which this chapter is devoted. 



EVIDENCE OF VERTEBRATES. 

 Known vertebrate fossils of the Denver and Arapahoe. As far as is kllOWU to the Writer, 



no vertebrate fossil had been described or positively identified from the 

 Laramie, Arapahoe, or Denver formations of the Denver Basin before the 

 beginning of the investigations recorded in this volume (lssi).' A few 

 had been found by Prof. A. Lakes, of Grolden, and during the progress of 

 the work a considerable number of hones were discovered by Mr. G. L. 

 Cannon, jr., of Denver, and by Mr. Eldridge and the writer. The collec- 

 tion of this material extended over a number of years The fossils 

 obtained were for the most part isolated bones or fragments, and all or 

 nearly all of them were sent to Prof. ' >. C. Marsh for examination. 



Owing to the fact that few connected pails of skeletons have been 

 found, and because the bones belong for the most part to new types, many 

 of them have as yet been identified only in a general way, yet a number 



A.8 mentioned in a latet section of ibis ohapter, it is possible that certain dinosaurs and other 

 vertebrate i">>hmIs from Bijou Creek, described by Professor Cope, came from strata of Arayiahoo age. 

 flu locality is beyond the limits of the Denver Basin as the term is here used. 



