638 EEPOET UNITED STATES GEOLOGICAL SUEVEY. 



some nearly an incli long, and others minute and in prodigious numbers. 

 With them are found stems of plants, but no leaves." * 



Similar fossils were found on the Big Sandy in 1873 by Professor Com- 

 stock, and invertebrate fossils were obtained from the group just south 

 of our hue on Ham's Fork. ■\ 



The best fossil locality visited by us was on Twin Creek, at the south 

 end of the Ham's Fork Plateau. This has yielded a large number of 

 fossil fishes that have been described by Professor Cope in the Bulletins 

 of the Survey. Associated with the fish are large numbers of leaves and 

 insects. Of the insects all I collected Professor Scudder thinks repre- 

 sent a single species described in the Canadian reiDort for 1877, not yet 

 published. He says, " I have not yet given these specimens of yours all 

 the attention they require." 



A few leaves were collected a few lailes north of this locality. They 

 were leaf of a new species of Myrica, and an involucre of Ostrya, new 

 species. Of these, Professor Lesquereux says, " Both these are referable 

 to the Tipper Green Eiver Group, which is by the plants the equivalent 

 of the White Eiver Group." 



In connection with Unio Maydeni, on Ham's Fork I found fragments 

 of what appeared to be fossilized branches. Professor Lesquereux says 

 one of them has the pith grooved like an Equisetmn. With these occur 

 millions of Cypris. 



At the mouth of the Little Sandy, in connection with invertebrate 

 remains, I obtained fragments of broken and rolled wood, which were • 

 not determinable. 



The most interesting collection from the group was that of caddis-fly 

 cases from near Horse Creek Valley, in the Green Eiver Basin. The 

 following in relation to them, by Professor Scudder, is quoted from jS"o. 

 2, Vol. lY, Bulletin of the Survey, pp.' 542, 543 : 



Indusia calculosa. — In certain parts of Auvergne, France, rocks are fonnd, wliicli, for 

 a tliickuess of sometimes two m.eters, are wliolly made up of the remains of tlie cases 

 of caddis-liies. Tliese have "been f i eqnently mentioned by writers, and -Sir Charles 

 Lyell figures them in his Manual. Oustalet, in his recent treatise on the fossil insects 

 of Auvergne, describes two forms,t one from Clermond, and the other from St. Gerand, 

 which he distinguishes under the names Fhryganea corcnima and P. gerandina, princi- 

 pally from their difference in size and strength, and a distinction in the minute shells — 

 species of Fultulina — of which the cases are com]30sed. One of them, however, probably 

 the former, was i)reviously named by Giebel § Indusia tabulata, a generic name Avhich 

 it would perhaj)s be well to emx^loy for the cases of extinct Fhrijganidce, until they can 

 reasonably be referred to particular genera. 



During the past season, Dr. A. C. Peale, in his explorations under the Survey, dis- 

 covered on the west side of Green Eiver, Wyoming Territoiy, at the mouth of Lead 

 Creek \_This should ie Horse Creek. fVhen the fossils were sent to Professor Scudder there 

 was some douht as to the name of the creek. The locality is Station 14, soutli, of Morse Creelc 

 and ivest of Green liiver'}, in deposits which he considers as probably belonging to the 

 Upper Green Eiver Group, or i^ossibly to the lower part of the Bridger Group beds of 

 limestone, the upper floor of which is comxdetely covereil Avith-petrified cases of caddis- 

 liies, all belonging to a single species, which may bear the name we have ap])lied to 

 it above. II They vary from 14 to 19""" in length, from 4 to .5""" in diameter ;it their 

 open anterior extremity, and from 3 to 3.2""" at their posterior end, the thickness of 

 the Avails being about 6.75™'". As will be seen by these measurements, the cases are 

 a little larger at their mouth, but otherwise they are cylindrical, taper with perfect 

 regularity, and are straight, not ilightly curved, as in many Phryganid cases. 'I'hey 

 are completely covered with minute, rounded, water-AVorn])cbbles, apparently of quartz, 

 geuerallj' subsi^herical or ovate, and varying from one-third to two-thirds of a milli- 



*Eeport U. S. Geol. Survey, 1873, 1874, pp. 439, 440. 



tEeport on Eeconnaissance of Northwestern Wyoming by W. A. Jones, 1873, p. 124. 

 t Bibl. ficole Haut. fitudes; Sc. Nat. iv, art. 7, pp. 101-102. 

 \> Ins. der Vorw. 269. 



II I have since identified the beds as the base of the Green Eiver Group, or possibly 

 the toi) of the Wahsatch Group. 



