120 The American Geologist. August, li 
be questioned. If the teeth of both kinds belong to the same 
genus, there is no need of Leidy's name Anblvsodon ; which 
proposition is equally trite in the other case. Marsh has set 
aside, as types of Anblvsodon mirandus, the teeth represented 
by figures 41-45 of plate ix, of Leidy's paper in volume XI of 
the Transactions of the American Philosophical Society, i860. 
Mr. Lambe has figured a similar tooth and referred it provis- 
ionally to Ornithomimus. If this shall prove correct, the spec- 
ies must lie known as ( )rnithomimns mirandns. A criticism or 
two may be made on Mr. Lambe's nomenclature. He has re- 
ferred some scales of a fish to Lepidotns Leidy. Similar scales 
have been found by Dr. Williston which were accompanied by 
the peculiar vertebrae of Lepisosteus ; and in looking over some 
Judith river materials collected by Sternberg for Cope. I find 
similar vertebrae. This makes it probable that the scales from 
the Belly River beds belong to Lepisosteus. Mr. Lambe has 
identified some cranial bones of fish with Cope's Ceratodus 
eruciferus, but has placed them in the genus Rhineastus, a 
Bridger genus of Siluroids. It is doubtful whether Cope's 
type belongs to Ceratodus. but it is quite as unlikely that it 
belongs to Rhineastes. Mr. Lambe has provisionally associated 
with these bones some fragmentary spines. In Mr Brown's 
collection referred to above there is a nearly complete spine 
which resembles those found by Mr. Lambe. and this certainly 
does not belong to Rhineastes ; since it is not serrated behind 
and does nut form the peculiar articulation with the interueural 
that is found in Rhineastes. 
In these discussions it must be kept in mind that the iden- 
tifica.tions of species may not always be correct. The mater- 
ials found are likely to be fragmentary ; and whether so or not. 
they must often be compared with fragmentary types. The 
path of the vertebrate palaeontologist is beset with many pit- 
falls. 
Of the papers of professor Osborn and Mr. Lambe espec- 
ially it may be said that they have awakened an interest that 
will nut subside until some important questions have been de- 
cided. If the Belly River beds have the position that is claimed 
for them, Mr. Lambe has the satisfaction of knowing that he 
has brought to light the very oldest known forms of several 
genera. 
