102 CALIFORNIA ACADEMY OF SCIENCES [Proc. 47H Ser. 
sistent in character, and can be followed farther through the 
field than any others that have been attempted. A prominent 
layer of white sandy marl with an abundance of vertebrate 
remains can be followed easily for many miles. 
Mr. Charles Morrice has recently collected from a small 
area in this zone an enormous number—1500 or more—of 
vertebrate fossil remains, including the teeth of many species 
of sharks and skates, the jaws and teeth of sea-lions, bones of 
whales, etc. Some of the sharks are probably undescribed 
species. Teeth of a Desmostylus have been obtained also from 
the same locality. It seems remarkable that so many remains, 
including diverse species, could be assembled in so small an 
area, which, at the time of their deposition and burial, must 
have been considerably off shore. Probably they mark an 
epoch of abnormal destruction among marine veretebrates, 
possibly an epoch of violent volcanic activity accompanied by 
the fall of ash, etc. 
As has been already stated, the teeth and other remains found 
at other horizons than Zone C, are often found just beneath 
beds of volcanic ash, or in beds in which ash makes up an 
important part. 
As will be seen, the faunas of the three prominent zones 
already described belong to the lower division of the Neocene, 
and are characteristically Lower Miocene. The upper division 
as far as known is almost without fossils, and is barren of any 
forms that are serviceable for stratigraphic correlation. 
FOSSILS FROM THE ESTUARINE BEDS 
Among the invertebrate fossils occurring in the estuarine 
beds of Caliente Creek, Dr. Dall has recognized land shells 
belonging to the genera Circinaria and Epiphragmophora. In 
addition to these a species of Corbicula near C. dumblei occurs 
in great abundance in one or more beds near the top of the 
series. 
No special effort was made to collect or to determine the 
land plants contained in these beds, though, along with ferns, 
etc., the following genera were recognized: Salix, Platanus, 
Ficus. Other genera, however, were observed and also col- 
lected. 
