1895.] Geology and Paleontology. 923 
Near the beginning of the Upper Jura this connection with Euro- 
pean waters was cut off, and one established with those of Siberia and 
northern Europe, bringing in a Boreal fauna. 
This same connection was continued through part of the Lower 
Cretaceous, giving a boreal fauna to the Knoxville. 
Near the beginning of the Gault, connection with the Boreal sea of 
Russia was cut off, and communication established with southern India 
and through that country with central and southern Europe, bringing 
in a warm-water fauna. This connection existed during the greater 
part of the Cretaceous, but after this time the faunas are confined much 
more closely to their present ranges, although even to-day many of our 
living and Tertiary mollusca are found in Japan. 
These changes in faunal geography are too widespread and easily 
correlated over great areas to be charged to mere mountain-making ; 
they must rather be of the nature of continental uplift and subsidence. 
A study of these changes will throw light on the problem of the extinc- 
tion of faunas and explain the great poverty of certain beds, in which 
the conditions for life seem favorable. 
The fauna of California has not been a genetic series, but rather a 
succession of independent faunas, derived by migration from various 
parts of the earth, complicated 'by the mixture with the products of 
local development. Therefore, the student that would intelligently study 
the genesis and history of this fauna, must not neglect the fossil records 
of any region, since all may have contributed some elements to this 
complex assemblage of forms. 
A new Geomyid from the Upper Eocene.—A rodent from 
the Uinta beds (Upper Eocene) of Utah, representing a new genus, is 
described by Prof. W. B. Scott in the Proceeds. Phila. Acad. 1895, p. 
269 under the name Protoptychus hatcherii. The skull only is known, 
including the dentition of the upper jaw, but this proves to be of un- 
‘usual interest and brings to light some unexpected facts which are thus 
summarized by the author: 
(1). Protoptychus, a new rodent from the Uinta Eocene, is an unex- 
pectedly modernized form, which has already acquired very large mas- 
toid bullae, a rostrum, incisive foramina and posterior nares greatly 
resembling those of the jumping-mice, and, as in that family, the arti- 
culation of the jugal with the lachrymal is retained. The infraorbital 
foramen is of the murine type. The dentition and the shape and con- 
struction of the mastoid and surrounding parts of the cranium most re- 
semble those of the Heteromyidae. 
