white.] LARAMIE FOSSILS OF DANFOETH HILLS. 213 



west of the Eocky Mountains ; but its position east of the mountains 

 is apparently near the base of the group. 



8. Corbula undifera Meek. 



This species was described by Meek in the Annual Eeport of the 

 United States Geological and Geographical Survey of the Territories 

 for 1872, p. 513, from the Laramie strata at Eock Springs in the valley 

 of Bitter Creek. In Powell's Eeport on the Geology of the Uinta Mount- 

 ains, p. 129, 1 described another form under the name of G. subundifera 

 from a higher horizon of the Laramie strata of the same valley, which I 

 now regard as only a variety of Mr. Meek's species. The original variety 

 has been found only at Eock Springs and at the Danforth Hills locality. 

 The variety subundifera was originally found at Point of Eocks in 

 Bitter Creek Valley, and I have also recognized it among some fossils 

 brought from Upper Kanab, Southern Utah, by Professor Powell. The 

 two varieties thus seem to be quite constant. 



9. Melania wyomingensis Meek. 



The wide geographical distribution of this species, as well as its char- 

 acteristics, has already been commented on under the head of notes on 

 the Laramie fossils of Crow Creek Valley. Its occurrence here not only 

 adds to our knowledge of its distribution, but also to that of its vertical 

 range in the Laramie Group. Its position at the original locality in 

 Bitter Creek Valley, and also at that of Yanrpa Valley, is near the top 

 of the group. At the Danforth Hills locality its position is near the 

 base of the group, showing the known vertical range of the species to 

 be about 3,000 feet. It is a noticeable fact that all the associates of this 

 species at the Danforth Hills locality are brackish-water, or perhaps in 

 part marine species, none being purely or exclusively of fresh- water habi- 

 tat. It is also a singular fact that while other fresh- water forms are some- 

 times associated with it, some of its associates at all the localities where it 

 has been discovered are brackish-water forms, or those that may have 

 inhabited both fresh and brackish waters. The characteristics of the 

 shell are such as to scarcely admit of a doubt that it is either a true 

 Melania or a very closely allied form. 



10. Od&ntobasis f formosa. 



Only a single example of this species was discovered. It is imperfect, 

 and perhaps does not belong to that genus, to which it is referred pro- 

 visionally. It is published in the Bulletin of the United States Geolog- 

 ical Survey, vol. iv, p. 718, and also in this volume, with a figure. 



11. Cytlierina? 



In the fine-grained indurated reddish shales of this locality are nu- 

 merous casts of an Ostracoid crustacean which I refer provisionally to 

 Cytlierina. These are the first examples of that order of crustaceans, 

 so far as I am aware, that have been discovered in strata of the Laramie 

 Group. 



12. Fish remains. 



A few cycloid scales were also found in these shales, which, except a 

 few s imil ar examples found in Bear Eiver Valley, are the only fish re- 

 mains discovered by inyself in Laramie strata ; but there seems to be no 

 reason why fishes may not have existed abundantly during that period. 



The absence of the Ostrea here is noticeable, and is probably due to 

 the uncongeniality of habitat that was produced by the fine sediment 

 which now constitutes the shales. 0. glabra was found further down the 

 valley of White Eiver in strata fully as near the base of the group as 



