602 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



Wind River Valley, and they were described by Meek and Hay den, 1 who 

 had previously 2 announced the discovery of Jurassic fossils from the Black 

 Hills. These Black Hills fossils are fully described and illustrated in the 

 Paleontology of the Upper Missouri. Subsequent geological explorations 

 and surveys have shown that the marine Jurassic is widely distributed in 

 South Dakota, Wyoming, Montana, Idaho, and Utah, and have made con- 

 siderable additions to the fauna that have been described by White, 3 Hall 

 and Whitfield. 4 Meek 5 and Whitfield. 6 All of these authors seem to have 

 assumed that the fossils they described belonged to a single fauna, At 

 least they made no attempt to recognize distinct horizons in the Jurassic. 

 The meagerness of the fauna — usually only a few species having been 

 obtained at any one locality — was perhaps sufficient reason for not making 

 attempts of this kind. Prof. Alpheus Hyatt's recent comprehensive studies 

 of the earlier Mesozoic faunas of the United States, and especially of Cali- 

 fornia, where all the greater divisions of the Jura are developed, have led 

 him to express the opinion that both the Upper Jura (Callovian or Oxford- 

 ian) and the Middle Jura (Oolite) are represented in the Rocky Mountain 

 region. 7 In the former he places the Jurassic of the Black Hills, and of 

 Red Buttes and Aurora, Wyoming, with probably some localities in Utah. 

 Of the Middle Jura he says: "The Oolite certainly seems to have been 

 found by Dr. Peale near the lower canyon of the Yellowstone in Montana, 

 and out of the few fossils from Utah described by Dr. White some are 

 closely similar to those of the inferior Oolite at Mount Jura." 



It has already been stated that this collection of Dr. Peale's belongs 

 to the same horizon that is represented in the Park. It contained the fol- 

 lowing species: 



Ostrea strigilecula. Trigonia niontanaensis. 



Grypkpea planoconvexa. Astarte ineeki. 



Camptonectes platessiformis. Cypricardia haguei. 



Pinna kingi. Pleuromya subconipressa. 



Gervillia montanaensis. Pholadomya kingi. 



Modiola subimbricata. Goniomya montanaensis. 

 Trigonia americana. 



1 Proc. Acad. Nat. Sci. Phila., 1861, p. 437, and Paleontology of the Upper Missouri, 1865, pp. 74 and 80. 



^Pi-oc. Acad. Nat. Sci. Phila., 1858, pp. 46, 49-59. 



3 U. S. Geog. and Geol. Expl. West of 100th Meridian, Vol. IV, Pt. 1, 1875. 



<U. S. Geol. Expl. 40th Parallel, Vol. IV, Pt. II, 1877. 



5 Idem, Pt. 1, 1877, and Simpson's Rept, Expl. Great Basin, Utah, 1876. 



"Newton and Jenney's Rept. Geol. Black Hills of Dakota, 1880, pp. 344-382. 



"Bull. Geol. Soc. Am., Vol. Ill, 1892, pp. 409-410. 



