760 HISTORICAL GEOLOGY. 



The Jurassic of Dakota, Wyoming, and Utah have afforded Ostrea stringilecidat 

 Tancredia extensa, Camptonectes bellistriatus, and the Ammonite Quenstedioceras cordi- 

 forme. That of Idaho afforded AVhite : Pentacrinus asteriscus, Ostrea sO'ingilecula, 

 species of Tancredia, Trigonia, Myacites, etc. In the Uintah Mountains, where the 

 rocks are shales and sandstones with limestone, occur Pentacrinus asteriscus, Belem- 

 nites densus, Trigonia, Gryphoia calceola, Myophoria lineat.a, Camptonectes bellistriatus, 

 Eumicrotis curta, etc. ; and in the Wasatch have been found Cucullcea Haguei, Myophoria 

 lineata, Myacites subcompressa, Volsella scaZpra (King's Report on the 40th Parallel). 



In the West Humboldt region, west Nevada, occur Belemnites Nevadensis, species of 

 Montlivaltia, etc.; and probably from this region came the Ammonite, Arnioceras 

 Humboldti; in Esmeralda County, Nev., Vermiceras Crossmani, Arnioceras Nevadense; 

 in Inyo County, Cal., Arnioceras Woodhulli. 



Jurassic beds at Taylorville, Cal., on the Sierra Nevada, afforded Hyatt, in the lower 

 beds referred to the Lias, besides the most of the above genera, species of Pinna, 

 Entolium, Goniomya, Pleuromya ; also an Echinoderm of the genus Cidaris and a 

 Crustacean of the genus Glyphcea. The Middle Oolytic beds contain, among the species, 

 Ammonites of the genera Grammoceras and Sphceroceras ; and the Upper Oolyte, species- 

 of the genus Bhacophyllites, with 3 species of Trigonia in the lower bed referred to the 

 Callovian division of the Oolyte, and several species of Coral of the genus Stylina referred 

 to the Corallian, besides the Camptonectes bellistriatus Mk. , and the Bhacophyllites of the 

 Upper Oolyte. Hyatt speaks of the contrast of the species with those of the summit region 

 of the Black Hills, southeastern Wyoming, whose Ammonites are of the Cardioceras^ 

 family and whose beds are Callovian or Oxfordian. 



The Mariposa beds extending to near Colfax, Placer Comity, Cal., contain, according^ 

 to Hyatt, Cardioceras duhium of Oxfordian age, and striated Aucellm (Figs. 1203-1205) in 

 great numbers, Perisphinctes of the same types as those found in the Upper Jura, Upper 

 Oxfordian, and Volgian of Russia, namely, Perisphinctes virgulatiformis, P. Colfaxi, 

 P. Muhlbachi, and Belemnites Pacificus. None of these species pass into the Knoxville 

 beds. 



The Queen Charlotte beds have afforded Whiteaves (Mesozoic Foss., Can. Survey, 

 1884) species of the Ammonite group of the genera Lytoceras, Haploceras, Ancyloceras 

 {A. Bemondi of Gabb), Hamites, and also species of Trigonia, Inoceramus, Aucella, 

 Amusium, Yoldia, etc.; also Belemnites densus. 



Among the Arctic fossils of this period, there are, at Prince Patrick Island, Ammo- 

 nites M'' Clintocki, a species near A. concavus Sow., of the Lower Oolyte; and at Cook's 

 Inlet, Ammonites WosnessensM, A. biplex Sow. (?), Belemnites paxillosus (B. niger List ?)^ 

 and Pleuromya unioides Br. (Unto liassinus Schubler). A. biplex also is reported to 

 occur in the Chilean Andes, in latitude 34'^ S., as well as in Britain and Europe. 



1. Fishes. — Fishes are rare fossils. The teeth of Ceratodus Giintheri of 

 Marsh have been described from the Upper Jurassic (Atlantosaurus beds) 

 of Colorado. 



2. Reptiles. — The Upper Jurassic formation of Colorado and Wyoming has 

 afforded remains of a few Amphibians, many great and small Eeptiles, and 

 of some Mammals. The specimens are thus far from the " Baptanodon and 

 Atlantosaurus beds " of Colorado and Wyoming. They include Sea-Saurians 

 related to the Ichthyosaurs (page 784), and also Dinosaurs, Crocodilians, 

 Turtles, and Pterosaurs or Flying Eeptiles. 



Enaliosaurians (Ichthyopterygians). — These Sea-Saurians are the most 

 fish-like of Eeptiles. This appears (1) in their biconcave vertebrae (Fig. 



