Literature on the Laramie Formation. — Hay. 119 
Bellv River species three, Trionvx vagans, Adocus lineolatus, 
and Bottosaurus perrugosus, were described from northeastern 
Colorado, from probably the Arapahoe beds, which Whitman 
Cross places above the typical Laramie. Again. Mr. Lamb's 
mammal, Ptilodns primaevus, belongs to a genus which is 
otherwise known only from the Torrejon Eocene. Indeed, if 
we exclude all genera known only from Belly River and Lar- 
amie deposits, we shall find that not more than three are rep- 
resented by species older than the Pierre, while no fewer than 
eight are known from the Tertiary. 
As bearing on this question may be mentioned some mater- 
ials which were collected by Mr. Barnum Brown, in 1902. for 
the American Museum of Xatural History. On Hell creek, 
twelve miles north of the Missouri river, and 130 miles north- 
west of Miles City, Montana, there were found remains which 
are identified as follows : 
Lepisosteus occidentalis Champsosaurus 2 sp. 
(Leidv). Crocodylus humilis. 
Compsemys victus (Leidy). Ornithominus sp. 
Adocus lineolatus (Cope). Monoclonius sp. 
Basilemys variolosus (Cope). Triceratops sp. 
Trionvx vagans (Cope).) Deinodon mirandus (Marsh). 
T. foveatus (Leidy). Dryptosaurus sp. 
Plastomenus costatus (Cope). 
This list resembles much, so far as it goes, the one pub- 
lished by Mr. Lambe; and yet the materials were found be- 
tween one and two hundred feet above the Pierre deposits ( as 
indicated by the invertebrates identified by professor R. P. 
Whitfield), and most of the others above a fine skull of Tri- 
ceratops. 
The writer may be permitted to make an additional remark 
on professor Osborn's first paper. On page 18 this author 
states that the present writer is of the opinion that Cope was 
justified in rejecting the name Deinodon. This is an error. 
What the writer holds is that Cope was justified in restricting 
the name Deinodon, limiting it to those teeth originally de- 
scribed under the name Deinodon horridus which have a D- 
shaped section. If these teeth belong to a different genus from 
those with opposite cutting edges, a- Cope, Leidy. and Marsh 
all have believed, then the binding force of Cope's action cannot 
