96 REVIEWS 



of the eastern basins of accumulation. There are no related forms in 

 the Middle John Day. With the exception of Promerycochcerus, and 

 possibly some of the Rhinoceroses which have not yet been fully worked 

 up, all the ungulate genera of the John Day are the same as those of 

 the White River. 



The Upper John Day has its closest affinities with the Middle John 

 Day, and is probably in greater part Upper Oligocene, although it may 

 overlap on the Lower Miocene. The Middle John Day is to be corre- 

 lated with the Protoceus horizon of the White River Oligocene. The 

 lower limit of the Upper John Day is determined by the downward 

 range of Promerycochcerus in the beds. 



This genus, which also occurs in the Mascall, and Mylagaulodon 

 angulafus, gen. and sp. nv., and later types unite in a measure the gap 

 between the Upper John Day and the Mascall faunas. 



The presence of Desniatippus crenidens in the Mascall serves to 

 correlate this formation with the Deep Riverbeds. The flora preserved 

 in the lower levels of the Mascall formation determines its age very 

 definitely as Upper Miocene. 



The Columbia lava represents in the stratigraphic series an erosion 

 interval between the Upper White River and the Loup Fork in the 

 plains region. 



The Valley of Southern California. By E. W. Hilgard, Berkeley, 

 Calif. 



This paper treats of the orographic relations and post-Tertiary 

 formations of the valley region extending from Los Angeles to Red- 

 lands, showing it to have been a topographic unit anterior to the subdi- 

 vision of the drainage into the San Gabriel and Santa Ana systems by 

 the extraordinary development of debris fans which now form the 

 sources of artesian waters. 



The Potter Creek Quaternary Bone Case. By Wm. J. Sinclair; 

 presented by J. C. Merriam. 



The case, which is situated near Baird, Shasta county, Calif., con- 

 tains a thick deposit of alternating layers of clay, case breccia, and 

 stalagmite resting in part on a stratum of volcanic ash. The ash 

 reposes, either directly or with the intervention of some clay, on a 

 floor of cemented case breccia known to be in part about a foot and a 



