MESOZOIC CHANGES IN FAUNAL GEOGRAPHY. 381 
character, having many species in common with that region, but 
being entirely cut off from the Californian. 
CRETACEOUS FAUNAS. 
Knoxville—At the beginning of the Lower Cretaceous of 
California, as in the Upper Jura, we find that the closest affinities 
with foreign faunas are with the Volga stage of Russia. These 
beds and their faunas have been described by W. M. Gabb in the 
Paleontology of California, by J. S. Diller and T. W. Stanton,* 
and. a similar fauna has been described from Queen Charlotte 
Islands by J. F. Whiteaves.*? In the papers cited it has been 
shown that of the Knoxville fauna the following species are 
nearly related to Russian forms: dAwcella prochi, Gabb, very near 
A. mosquensis, Buch; A. crassicollis, Keyserling, probably identical 
with the Russian species; A. prochz, var. ovata, possibly identical . 
with A. terebratuloides, Lahusen; Olcostephanus att. discofalcatus, 
Lahusen. And besides these there occurs Hoplites aff. ambl- 
gonius N.andU. These are sufficient to show a close faunal con- 
nection with Russian waters. 
In addition to the species mentioned there are others of a 
Tithionan aspect, so that we have certainly the lowest Cretaceous 
and possibly the top of the Jura. Mr. Diller, in his various 
papers, has shown that the lowest Knoxville beds are separated 
from the highest Jura by a decided unconformity, but this does 
not represent any long time interval, and is not accompanied by 
any great change in life. The faunal geography was the same 
as at the close of the Mariposa epoch, and no new elements had 
come in; the change was due to development and intermigration 
between this region and Russia. Rocks of this age are unknown 
in India, so of the relation with southern Asia nothing can be 
said. 
Horsetown.—In the Horsetown, or Gault, fauna it is seen that 
a great change has taken place; these beds lie conformably on 
the Knoxville, yet the Russian elements have nearly all died out, 
t Bull. Geol. Soc. Am., Vol. IV., pp. 205-224; Vol. IV., pp. 245-256; Vol. V., pp. 
435-464. 
2Geol. Survey Canada, Mesozoic Fossils, Vol. I., Parts I. and III. 
