The Past 7 



contour feathers, which cannot be assigned to any particular sort 

 of bird. On one occasion, long thread-like strands were found, 

 closely resembling the plumage of the cassowary. It was inferred 

 that these might belong to a species of Diatryma, a gigantic flight- 

 less bird of the Rocky Mountain Eocene, now well known from 

 a skeleton found in Wyoming. Some of the paleontologists at 

 the British Museum believe that the remains are really vegetable 

 fibers, and not plumage at all, but it seems to me that they are 

 mistaken. It is indeed possible to make mistakes in dealing with 

 such fossils, and no less an authority than Lesquereux, who was 

 an expert student of mosses as well as fossil plants, described a 

 feather in the Florissant shales as a kind of moss, calling it Fon- 

 tinalis pristina. 



Of all the fossils in the oil shales the insects are the most 

 interesting. In the first place, we have from the Green River for- 

 mation about 300 different species, whereas for the Eocene depos- 

 its of all the rest of the world we know only about seventy. Then 

 it must be noted that the Cretaceous or Upper Mesozoic has so 

 far furnished only the most scanty and most imperfect remains of 

 insects, and back of that the insect fauna is of a relatively archaic 

 type. Thus the Green River shales furnish us with the first 

 (earliest) modernized series of insects, and in spite of the fact that 

 these rocks are many millions of years old, the aspect of some of 

 the species is in no way more archaic than that of those we catch 

 in Colorado today. The most striking illustration of this is found 

 in a wasp (Hoplisus archoryctes) discovered in the rock at the head 

 of Bear Gulch. It is as old as any wasp known, but its beautiful 

 preservation with wings outspread, shows that it is as like the 

 living forms of the genus as they are to one another. Even the 

 clouding on the wings is the same. Since that wasp lived, the 

 Himalayas and Swiss Alps have been raised to their present 

 imposing dimensions, but the wasp-protoplasm has gone on faith- 

 fully reproducing itself with only minor or specific changes. It 

 must not be inferred, however, that all the insects are of modern 

 or ordinary types. The earliest known ants occur in these deposits, 

 and one of them, (Archimyrmex rostratus), is a very singular 

 creature belonging to the family Poneridae. The bull-dog ants 

 of Australia, considered to be the most generalized of all living ants, 

 had only one known fossil relative, which was discovered in Baltic 



