MESOZOIC CHANGES IN FAUNAL GEOGRAPHY. 379 
Upper Jura.— The Upper Jura of California has been described 
from Plumas county and from the Mariposa formation of the 
Goldy Belts byash be Mice rin Vor Me vor the Loval-eontology. of 
California ;’’ by Professor Hyatt,t and by the writer.’ 
The fossils described by Professor Hyatt from the Callovian 
and Corallian of Plumas county are of rather indecisive character, 
but seem to have their nearest affinities with central European 
species. This makes it probable that throughout the Callovian 
and part of the Oxford these waters were still connected with 
the central European. But at this same time there existed in the 
region of the Black Hills of Dakota and the Rocky Mountains a 
basin that contained a different fauna, and according to Pro- 
fessor Hyatt3 was separated from the Californian basin. This 
central basin contains what Neumayr* has shown to be a 
decidedly Boreal fauna. In the paper referred to, Neumayr 
divided the Jura of the northern hemisphere in three distinct 
types, equatorial, temperate and Arctic. The Arctic or northern 
type occurs chiefly in Russia, and is characterized by the preva- 
lence of Cardioceras and Aucella, and the absence of reef-building 
corals. Neumayr’ has shown that the Black Hills Jura is a 
southern extension or bay of the Arctic sea. 
It therefore becomes probable that during Oxford times the 
California area was still connected directly with the central 
European waters by way of the ‘Central Mediterranean Sea,” 
and that the Black Hills basin was cut off from this, but con- 
nected with the Boreal sea of Russia. 
Transgression of Upper Malm.—Iit has long been known that 
in Europe in the Middle Jura the sea began to transgress east- 
wards over the land until in the Upper Jura or Malm all eastern 
Europe and nearly all Asia were under water. This has been 
described by Neumayr® as one of the most striking events in 
t Bull. Geol. Soc. Am., Vol. III., pp. 395-412; and Vol. V., pp. 395-434. 
2 Bull. Geol. Soc. Am., Vol. V., “Age of the Auriferous Slates of the Sierra Nevada.” 
3 Bull. Geol. Soc. Am., Vol. III., p. 410. 
4 Denkschr. K. Akad. Wiss. Wien., 1883, pp. 301-302. 
5 Loc. cit. 
©Geographische Verbreitung Juraformation, pp. 126-129. 
