abstracts: paleontology 327 



The papers are here assembled and to them is added a bibUography of 

 Survey publications on the minerals considered in the volume. 



R. W. Stone. 



PALEONTOLOGY. — Pliocene and pleistocene fossils from the Arctic 

 coast of Alaska and the auriferous beaches of Nome, Norton Sound, 

 Alaska. William HealEy Dall. U. S. Geological vSurvey 

 Prof. Paper 125-C. Pp. 23-37, pis. 2. 



Describes briefly the Tertiary geology and indications of changes 

 in elevation and climate. The intercommunication of Atlantic and 

 Pacific faunas in Pliocene time and the routes of migration of faunas 

 are considered. 



The author concludes that neither the Aleutian chain nor Bering 

 Strait has offered a bridge between continents since Miocene time and 

 it is evident that postulated land bridges must have existed in some 

 other place or the assumed migration must have taken place over the 

 ice of the strait when frozen. The Pliocene fauna indicates a more 

 temperate sea than at present and there is evidence that a freer con- 

 nection probably existed in Pliocene time between the North Atlantic 

 and the Bering Sea regions. 



Species collected on the Northern Alaska coast are listed and new 

 species described. R. W. Stone. 



PALEONTOLOGY. — Sofne American Jurassic ammonites of the genera 

 quenstedticerds, cardioceras, and amoeboceras, family cardio- 

 ceratidae. Jno. B. Reeside, Jr. U. S. Geol. Survey Prof. 

 Paper 118. Pp. 38, pis. 24, fig. i. 1919. 



Gives systematic descriptions of several new species of ammonites 

 obtained mostly from the Sundance formation of Wyoming. The 

 numerous plates are exceptionally fine illustrations of the material 

 described, faithfully reproducing the minute details of structure and 

 form. R. W. Stone. 



PALEONTOLOGY. — Reptilian faunas of the Torre jon, Puerco, and 

 underlying upper Cretaceous formations of San Juan County, New 

 Mexico. Chas. W. Gilmore. U. S. Geol. Survey Prof. Paper 

 119. Pp. 68, pis. 26, figs. 33. 1919. 



This paper is based on the best single collection of fossil turtles 

 that has ever been made in the southwestern United States. The 



