1867.] 117 [Scudder. 



Harris. He called attention to the fact that Agrotis clandes- 

 tina when at rest has the surface of the wings horizontal in- 

 stead of arched one from the other, as in the other species. 



Mr. P, R. Uhler stated that he had collected the naked 

 chrysalids of Agrotis teh'fera at the base of maize plants in 

 Maryland. 



Mr. S. H. Scudder presented the results of an examination 

 of a small collection of fossil insects obtained by Prof Wil- 

 liam Denton in the Tertiary Beds of Green River, Colorado.* 



The specimens were brought from two localities, called by Prof. 

 Denton, Fossil Canon and Chagrin Valley, lying about sixty miles 

 apart. The rocks, in both cases, were the same ; above were beds of 

 brown sandstone, passing occasionally into conglomerate, alternating 

 with thin beds of bluish and cream-colored shales, all dipping to the 

 west at an angle of about 20° ; they contained fossil wood of decid- 

 uous trees, fragments of large bones, most of which were solid, and 

 turtles, perfectly preserved, and sometimes two feet in length. Prof. 

 Denton considered this sandstone as probably of Miocene age. Be- 

 neath these rocks were beds of petroleum shale, a thousand feet thick, 

 varying in tint from a light cream color to inky blackness, and filled 

 with remains of insects and innumerable leaves of deciduous trees. 



I have examined ninety specimens ; many of the little slabs contain 

 several species of insects, but the remains are often so fragmentary 

 and imperfectly preserved, that it is impossible to identify them. Out 

 of sixty-five different species, more than two-thirds belong to the 

 Diptera ; the others are mostly small Coleoptera, with a few Homop- 

 tera, Hymenoptera, Lepidoptera and Physopoda. Among the Diptera^ 

 MycetophiiidcB and Tipulklce are prevailing types ; the dipterous larvse 

 have not yet been determined, but they belong to groups otherwise 

 unrepresented on these stones ; some of them are apparently Mus- 

 cidce. The Homoptera are represented by genera allied to Issus, 

 Gypona and Delphax. A species of Alyrmica, one of Formica, and a 

 third hymenopterous insect represent that suborder ; a poorly pre- 

 served moth, apparently a Noctuid, is the only Lepidopteron, unless one 

 of the larvffi prove to belong to some genus resembling Limacodes. 

 Perhaps the Physopod, belonging to a group which has never before 

 been found fossil, is of the greatest interest; remarkably well pre- 

 served specimens occur, from which the insect can be wholly restored. 

 It differs so essentially from Heeger's illustrations of this group, that I 

 propose for it a new generic name, Palceothrips fossilis. 



* See also these Proceedings, Vol. x., p. 305. 



