638 REPORT 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 Corn- 

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

 of our hue on Ham's Fork, t 



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 

 fossfl 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 report 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 miles 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 Upper Green Eiver Group, which is by the plants the equivalent 

 of the White Eiver Group." 



In connection Avith Unio Haydeni, 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 Equisetum. 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 Yalley, in the Green Eiver Basin. The 

 following in relation to them, by Professor Scudder, is quoted from No. 

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



Indusia calculosa. — In certain parts of Auvergne, France, rocks are found, which, for 

 a thickness of sometimes two meters, are wholly made up of the remains of the cases 

 of caddis-flies. These have been frequently mentioned by writers, and Sir Charles 

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

 of Auvergne, describes two forms,* one from Clermoud, and the other from St. Gerand, 

 which he distinguishes iinder the names Phryganea coreniina and P. gerandina, princi- 

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

 species of Paludina — of which the cases are composed. One of them, however, probably 

 the former, was previously named by Giebel § Indusia iabulata, a generic name which 

 it would perhaps be well to employ for the cases of extinct Phryganidce, until tkey 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 Territory, at the motith of Lead 

 Creek [This should be Horse Creek. When the fossils were sent to Professor Scudder there 

 was some doubt as to the name of the creelc. The locality is Station 14, south, of Horse Creek 

 and west of Green Eiver'], in deposits which he considers as probably belonging to the 

 Upper Green Eiver Group, or possibly to tbe lower part of the Bridger Group beds of 

 limestone, the upper floor of which is completely covered with petrified cases of caddis- 

 flies, all belonging to a single species, which may bear the name we have applied to 

 it above. || They vary from 14 to 19 inm in length, from 4 to 5 mm in diameter at their 

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

 the walls being about 0.75 mm . 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 slightly curved, as in many Phryganid cases. They 

 are completely covered with minute, rounded, water-worn pebbles, apparently of quartz, 

 generally subspherical or ovate, and varying from one-third to two-thirds of a milli- 



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



t Report on Reconnaissanse of Northwestern Wyoming by W. A. Jones, 1873, p. 124. 

 i'Bibl. iScole Haut. Etudes; Sc. Nat. iv, art. 7, pp. 101-102. 

 § Ins. der Vorw. 269. 



|| I have since identified the beds as the base of the Green River Group, or possibly 

 the top of the Wahsatch Group. 



