IV 
LETTER OF TRANSMISSION. 
An especial advantage enjoyed in the preparation of this report con¬ 
sists in the fact that the author obtcained the fossils himself, and is thus 
familiar with their local relations. This is a point of much importance, 
since the fragmentary condition in which the skeletons of extinct vertehrata 
are usually found, furnishes opportunities for error or doubt which greatly 
curtail the value of the work. In the present instance, the autlror has 
^ admitted no correlation of fragments without the clearest evidence, and, 
where any uncertainty exists, has stated it. 
The number of species of extinct vertebrata obtained during the sea¬ 
son of 1874 may be enumerated as follows: 
? Triassic. 4 
Cretaceous. 13 
Eocene. 87 
Upper Miocene (Loup Fork). 30 
Postpliocene. 2 
13G 
I desire to return my acknowledgments for the many courtesies which 
1 have experienced, during my connection with the Survey, from yourself 
and from all of its officers ; and also to the following gentlemen, to whom I 
am under obligations for assistance of various kinds: General August 
Kautz, in command at Fort Garland, Colorado; Lieutenants Blair and 
Delany and Drs. Moffatt and Collins, of the same post; also to General 
Gregg, in command of the District of New Mexico. 
I am, with much respect, 
E. D. Cope. 
First Lieut. George M. Wheeler, 
Corps of Engineers, U. S. A., in Charge. 
