EET EEE T 

1891.] Notes on Mesozoic Mammaha. 611 
We look forward with great interest to Part III. of this series 
of papers, as this collection is a most valuable and interesting 
one; and the above review is not intended in any way to depre- 
ciate the importance of an increased knowledge of the Creta- 
ceous Mammalia. 

NOTES ON MESOZOIC MAMMALIA. 
BY O. C. MARSH. 
if HAVE recently received from Prof. H. F. Osborn a pamphlet 
entitled “ A Review of the Cretaceous Mammalia,” which is 
intended as a criticism of two of my papers, and is a character- 
istic addition to his previous publications on Mesozoic mammals. 
It is difficult to take this review seriously, as it contains no new 
facts, and is mainly an application of the author’s theories, which 
may, in part, prove to be true, but at present are without substan- 
tial basis. To attempt to refute all the assumptions he makes 
would involve a long discussion of known Mesozoic mammals, 
and take time from more important work. A brief notice of a 
few points, therefore, must suffice for the present. 
Every one familiar with Mesozoic mammals knows that the 
author of this review has never collected any, has no specimens 
of the kind, and has only seen a part of those belonging to others, 
who have shown them to him as a matter of courtesy, in some 
cases even when an investigation was intended or in progress. 
Of more than a thousand specimens of Cretaceous mammals on 
which my investigations are based, he has not seen a single one, 
and no others are known except a few fragments. Of several 
hundred specimens of Jurassic mammals which I have secured in 
the west, he has seen perhaps one-tenth; while of other Mesozoic 
mammals from this country, he cannot have seen in all more than 
a half dozen specimens. 
1 As presented to the Academy of Natural Sciences, Philadelphia, April 14th, 1891. 
desea ig with some sd negate in the Prosoedings of the Academy. 


