606 TIMOTHY WILLIAM STANTON 
marine life must have been very nearly the same in both but as 
we do not know where the faunas originated nor the direction 
and rate of migration we can not determine the exact time 
relations of the deposits. 
In the Washita division many of the elements of the Freder- 
icksburg fauna continue either unchanged or but slightly modi- 
fied. Among identical species that occur in the lower beds of 
the Washita Exogyra texana, Turritella seriatim-granulata and 
Schloenbachta acuto-carinata may be mentioned. The Engonoceras 
group" of ammonites also reappears in the upper part of the 
division. Ammonoids are more abundant in the lower Washita 
(Preston and Forth Worth beds) than in any other part of the 
Comanche series, though only a few types are represented. 
Besides those already mentioned, the large Pachydiscus bra- 
goensis (Shumard) and Hamites fremonti Marcou are abundant, 
and there is a large development of the genus Schloenbachia, 
mostly of the type S. fata (Sowerby). These forms together 
with the large Turrilites brazoensis Roemer, if occurring in Europe 
would probably be taken to indicate either uppermost Gault or 
lowest Cenomanian. A large development of littoral forms in the 
Denison beds of northern Texas, in the Tucumcari region of 
New Mexico, and in southern Kansas also gives the faunaa 
rather modern aspect. But its close relationship with the fauna 
of the underlying Fredericksburg division and the fact that the 
next succeeding fauna, that of the Timber Creek beds, contains 
species of Acanthoceras and other types resembling those that 
are characteristic of the Cenomanian in Europe tend to place it 
lower in the Cretaceous system. The uppermost beds of the 
Washita may possibly be as late as the Cenomanian, but the 
lower beds in which Schloenbachia is so abundant can hardly 
be more recent than the Gault. However this point may be 
decided, the most natural major plane of division in the Texan 
*This group including Ammonites piedernalis van Buch, frequently spoken of as 
“Cretaceous Ceratites,” or as “ Buchiceras,” in the broad sense in which it was origi- 
nally defined, is considered characteristic of the southern European or Mediterranean 
Cretaceous. 
