No. 2313. NEW SPECIES OF EOCENE INSECTS— COCKERELL. 235 



pretty Fulgoridae must have flitted about in abundance, looking 

 like moths. If there were also genuine moths and butterflies, they 

 must have been rather scarce, or some would have been found among 

 the hundreds of specimens examined. There is somewhat of a mys- 

 tery surrounding the ants, which certainly did not abound as they 

 did at Florissant. Scudder described a few species, but from very 

 poor materials. I have before me a few supposed ants, but in no 

 case can the precise characters be made out. A really satisfactory 

 Eocene ant is still lacking. 



From the typical Green River beds of Wyoming about 140 species 

 of msects are known. Although the Colorado-Utah series is assigned 

 to the Green River * it can hardly be contemporaneous with the 

 Wyoming rocks, as the insects of the latter are essentially distinct. 

 Only fifteen species are at present recognized as common to the Wyo- 

 ming Green River, and the Colorado-Utah series. These are five 

 Curculionidae, six Otiorhynchidae, two Caiandridae, and one each 

 of Sciomyzidae (Diptera) and Formicidae. It is not certain that 

 closer scrutiny and better materials will not rather decrease than 

 increase these numbers. Of course it is possible that the differences 

 may be due in part to different ecological conditions, though there is 

 no distinct evidence pointing in this direction. 



It must also be added that the several localities in the Colorado- 

 Utah field are probably not all contemporaneous, and it is very likely 

 that we may eventually recognize a number of distinct horizons. 



Dr. F. H. Knowlton writes me that he has looked over IMr. Win- 

 chester's fossil plants from the Cathedral Bluff region, and although 

 he has not had time to examine them minutely, very few seem to be 

 identical with those of the Wyoming Green River. Most of the 

 species are apparently new. Doctor Eoiowlton is also convinced that 

 there are several distinct horizons represented in Mr. Wmchester's 

 material. The insects now described come from two sources. In 

 recent years Mr. Dean E. Winchester obtained a fair collection, rich 

 in new species, while mvestigating the oil shales for the United States 

 Geological Survey. Much earlier Dr. S. H. Scudder collected "on 

 the crest of the Roan Mountains near the head of East Salt Creek in 

 Western Colorado, and on the buttes bordering the Wliite River 

 near the Colorado-Utah boundary."- Owing to the failure of his 

 health, Scudder was not able to complete the description of the rich 

 materials he obtained, and they have remained untouched to the 

 present day. I am extremely indebted to Dr. R. S. Bassler for the 

 photographs illustrating this paper, as well as for many courtesies. 



1 Winchester, Bull. 641-F, U. S. Geol. Survey, p. 140. 



2 Tertiary Rhynchophorous Coleoptera of the United States, p. 7. 



