ART. XXIV.-AN ACCOUNT OF SOME INSECTS OF UNUSUAL IN- 

 TEREST FROM THE TERTIARY ROCKS OF COLORADO AND 

 WYOMING. 



By Samuel H. Scudder. 



An examination of an extensive series of fossil insects recently ob- 

 tained in diflferent parts of tbe Eocky Mountain region has brought to 

 light a large number of remarkable forms. To illustrate this, and as an 

 indication of what we may expect further researches will reveal, I 

 have brought together in this paper a few examples from different 

 orders. These, however, are some of the most striking. It will 

 scarcely fail of remark that those which come from the Florissant beds 

 indicate a tropical relationship to a conspicuous degree. Perhaps this 

 selection may show it to a far greater extent than a more systematic 

 one would do ; but my studies are constantly revealing similar affinities, 

 leaving no doubt in my mind that the faunal elements of Tropical 

 America of to-day entered largely into the insect-life of the central 

 United States in Tertiary times. Similar tropical characteristics have 

 already appeared in other Tertiary insects I have examined, such as in 

 the Orthoptera previously described from Florissant, the Entimus, the 

 ApJiana, and perhaps the Cyttaromyia from White Eiver, and possibly 

 also the Litkortalis from British Columbia. 



The beetle described below [Parolamia rudis), however, is of an Old 

 World rather than a New World type. 



Perhaps the most generally interesting insect will be thought to be 

 the fossil butterfly {Prodryas perseplione), which is so perfect as to allow 

 description of the scales, and, besides being the first found in America, 

 is far finer than any of the nine specimens which have been discovered 

 in Europe, and shows, moreover, some features betokening its antiquity. 



The fly {Palemholus florigerus) is interesting, not only as representing 

 a highly specialized type hitherto unknown on this continent, but as 

 showing how the semblance of an original vein may be formed in the 

 wings out of mere fragments of distinct veins, affording, indeed, a better 

 example of this feature than living members of the same group in other 

 parts of the world. 



The insects from other places than Florissant are described on account 

 of their remarkable character. The eggs of the Corydalites are, so far 

 as I know, the first insect-eggs that have been found in a fossil state; 

 but aside from that, they have an intrinsic interest. The Dysagrion from 

 Green Eiver is of a marked troi)ical type; while the cases of the caddis- 

 fly enable me to draw the attention of collectors to the occurrence of such 



objects in a fossil condition. 



519 



