450 Mesozoic and Cenozoic of North America. [ May 
POSTCRETACIC SYSTEM. 
This name was proposed and afterwards abandoned by White 
for the lacustrine formations which rest conformably on the upper 
beds of the Cretacic (Fox Hills), whose paleontology will not 
permit them to be ranged with the Cznozoic system. The Ver- 
tebrata are as follows: 
Presence of Pisces Ginglymodi and Halecomorphi; Reptilia 
Choristodera ; Mammalia Marsupialia Multituberculata. Absence 
of Pisces Isospondyli Saurodontidz and Actinochiri; of Reptilia 
Sauropterygia and Pterosauria. 
There are two well-marked epochs of the Postcretacic,—the 
Puerco and the Laramie 
_ Laramtre.—Present:3+ - Pisces Elasmobranchi Myledaphus ; 
Reptilia Dinosauria Goniopoda and Orthopoda. Absent: Mam- 
malia Placentialia. 
This formation has an immense extent on the morthers plains 
in the United States 35 and Canada; along the eastern flank of 
the Rocky Mountains, and on the western flanks of the same in 
New Mexico, and along the Lower Rio Grande in Texas and 
Tamaulipas.’ It consists of sandstones, marls, and lignite, whose 
base rests conformably on the Fox Hills beds of the Cretaceous, 
when the latter is present. Thickness: 
Feet, 
East flank of Rocky Mountains, Colorado (King) 3..........ssss000 1500 
Southwestern Wyoming (King) 5000 
Upper Missouri, Montana (Cope) 3 500 
Northwestern New Mexico (Baldwin and Cope) » 2000 
A formation has been observed along the Belly River, in Sas- 
katchewan, by the geological survey of the Dominion of Can- 
ada, which they call the Belly River.* It is overlaid by the 
Pierre, and would be placed in the system in accordance with 
this position between that formation and the Niobrara below it. 
But the flora and the fauna, vertebrate and invertebrate, are 
identical, or nearly so, with that of the Laramie. The expla- 
nation of this singular state of the evidence has not yet been 
reached. 
- EERS Mammalia Placentialia. Absent: Pisces 
Elas aeta ranchi ; Tapia Dinosauria Goniopoda and Ortho- 
The fauna of this horizon is well distinguished from that of 
