FOSSIL FAUNA AND FLORA OF THE FLORISSANT SHALES 1 59 



inae. I may further add the unpublished fact that it is a peculiarity of the Tertiary 

 Staphylinidae of this country that the antennae and legs are measurably shorter 

 than in modem types; this is most marked in cases where the living and extinct 

 species of the same genera are compared. — Tertiary Rhynchophorous Coleoptera, 

 1893, p. 2. 



Thus we find, among the insects, indications of common trends 

 of variation similar to those observed by H. F. Osborn and others 

 among the vertebrates. Professor Osborn wrote in 1897: 



My study of teeth in a great many phyla of Mammalia in past times has 

 convinced me that there are fundamental predispositions to vary in certain direc- 

 tions; that the evolution of the teeth is marked out beforehand by hereditary influ- 

 ences which extend back hundreds of thousands of years. — Science, Oct. 15, 1897. 



The subject is further elaborated by the same author in the Amer- 

 ican Naturalist, April, 1902, and I have offered some theoretical con- 

 siderations in Nature, Dec. 28, 1905, p. 197. 



It remains to offer some remarks on the probable age of the Floris- 

 sant shales. I am informed that geology affords little help in this 

 matter, and for the present, we must rely wholly, or almost wholly, 

 on the evidence afforded by the fossils. The total absence, so far, 

 of mammals, reptiles, batrachians or land shells is much to be regret- 

 ted; it can hardly be doubted that further search will reveal some 

 members of one or other of these groups. In the meanwhile, it ought 

 to be possible to reach some conclusions from the very large series 

 of organisms already discovered. 



In the first place, it seems to me evident that we must cease to refer 

 to the Florissant shales as belonging to the "Green River Group," 

 unless that term is so extended as to be nearly meaningless. Mr. 

 Scudder wrote in 1893: 



The detailed study of the fossil Rhynchophora has made very clear and specific 

 one point which impressed me in general while working in the field, and that is 

 the wide difference between the character of the fossils obtained at Florissant and 

 those obtained at any of the other localities (perhaps excepting Elko, Nevada, of 

 which little is known) in the Rocky Mountain region. He goes on to specify 

 the differences in detail, and remarks that when we come to examine the species 

 of Rhynchophora, we shall find that while the three localities in western Colorado 

 and Wyoming share a number of forms in common not a single species found at 

 Florissant occurs in either of the others. 



