1894.] Geology and Paleontology. 953 
difference. These are given in detail and then summarized up in the 
following paragrap 
“In brief, the ee Gis and skeleton of Agrioclicerus shows a large 
number of close correspondences with the oreodonts, and especially in 
those particulars in which that group differs from other artiodactyl 
families. On the other hand, there are significant deviations from the 
oreodonts, which are to be found more particularly in the structures 
correlated with the curious change in foot structure. It seems on the 
whole highly probable that the two families are not distantly related, 
especially if the somewhat intermediate character of Protoreodon be 
considered." 
The conclusion arrived at by Dr. Scott as to the systematic position 
of Agriochcerus is that it is the last term in a succession of species 
which form a curiously specialized offshoot of the Oreodontide, its 
divergences from that family being principally the results of a change 
in the functions and uses of the feet. (Proc. Amer. Philos. Soc., Vol. 
XXXIII, 1894.) 
The Atmosphere as a Factor in Dynamical Geology.— 
The line of inquiry pursued by Mr. J. A. Udden, concerning the work 
performed by the winds of the atmosphere is important since this sub- 
ject has not received any searching attention from the geologists of 
this country. The author states a series of laws which appear to gov- 
ern aerial erosion, transportation and sedimentation in general, and 
gives the data from which these laws are formulated. The similarities 
and differences of wind and water erosion and transportation are 
pointed out, and estimates, based on experiments, of the relative values 
of the work accomplished by each. From these considerations impor- 
tant deductions are drawn. (1) Since the velocities in the atmosphere 
are greater than those in water, the distances over which materials 
may be transported in it are correspondingly greater. (2) The depth 
of the aerial ocean renders it but little dependent in its movements 
on the elevations of the land. (3) While the conditions requisite for 
aerial erosion are limited to rather small areas on the land of the 
globe, deposition is much more general and widespread. Hence accu- 
mulations of atmospheric sediments are insignificant, as a rule, only 
accumulating in exceptional cases. : 
In conclusion, Mr. Udden suggests that from a dynamical point of 
view the wind theory would appear to furnish an adequate explanation 
of the joceurrence of the loess in the Mississippi valley, at least as to 
