PALEONTOLOGICAL GEOLOGY ^ 
75 
Ancient Salt Lake Cannonball? Campbell makes the observa¬ 
tion that “It seems probable that the Cannonball member of the 
Lance formation is Tertiary in age, and that the Cretacic fauna 
which occurs it is merely a surviving remnant of an old Cretacic 
fauna which formerly lived in the open sea, but which as this sea 
became more and more restricted and eventually enclosed by land 
preserved its old forms even into Tertiary time.” 
It is not impossible that the Cannonball conditions were those 
of a bittern lake instead of those of an open arm of the ocean. 
All references to the organic remains assume that they form a 
marine assemblage. That they might just as well constitute a 
salt lake fauna is supported by many circumstances. 
The Fox Hills sea was a vast body of epicontinental waters 
which finally completely withdrew from the region. In the course 
of the withdrawal the strictly thalassic forms would naturally 
soonest disappear. If a considerable land-locked basin remain 
the littoral types which the thalassic forms removed might persist 
for a long time, perhaps until the lake entirely dried up. In this 
way apparently a marine deposit could exist in the midst of fresh¬ 
water, fluviatile and epirotic beds. Thus all the incongruous bi¬ 
otic difficulties are easily haarmonized. Paleogeographic features 
do not have to be modified. Diastrophic conditions are satisfied. 
Taxonomic discrepancies are removed. There are no compro¬ 
mises to be made among discordant factors. 
Scrutiny of the so-called marine aspects of the Cannonball hy¬ 
pothesis of the existence of a great salt lake seems worthy of full¬ 
est consideration. Keye:s. 
Northernmost Extension of Marine Eocene Beds in Mississippi 
Emhayment. There recently came into my hands, through the 
kindness of W. A. Nelson, State Geologist of Tennessee, a spec¬ 
imen collected by Erasmus Haworth six miles north of Campbell, 
at the northern extremity of the Crowley Ridge, in Dunklin Coun¬ 
ty, Missouri. This specimen is of especial interest since it is a 
good sized fragmei?/t of a one-inch band of gray, somewhat sandy 
limestone made up almost entirely of the shells of Ostrea pulask- 
ensis, Harris. 
This shell is a characteristic small ostreid form of the lower 
Midway section — one that is exceedingly common in Midway out- 
