204 Prof. O. C. Marsh—Comparison of Dinosauria. 
TV.—Comparison oF THE Principat Forms or DrnosavURIA OF 
Evurore anp AmMeErRiIca.! 
By Professor 0. C. Marsu, Ph.D., LL.D., F.G.S. 
HE remains of Dinosaurian reptiles are very abundant in the 
Rocky Mountain region, especially in deposits of Jurassic age, 
and during the past ten years the author has made extensive collec- 
tions of these fossils, as a basis for investigating the entire group. 
The results of this work will be included in several volumes, two of 
which are now well advanced towards completion, and will soon be 
published by the United States Geological Survey. 
In the study of these reptiles, it was necessary to examine the 
European forms, and the author has now seen nearly every known 
Specimen of importance. The object of the present paper is to give, 
in few words, some of the more obvious results of a comparison 
between these forms and those of America which he has investigated. 
With this purpose in view, it will not be necessary to discuss 
here the classification of the Dinosauria, their affinities, or their 
origin. These topics will be treated fully in the volumes in prepara- 
tion. For the sake of convenience, however, the ordinal names 
proposed by the author, and now in general use, will be employed. 
SAUROPODA. 
The great group which the author has called Sawropoda, and 
which is represented in America by at least three well-marked 
families, appears to be rare in Europe. Nearly all the remains 
hitherto discovered there have been found in England, and most of 
them in a fragmentary condition. The skull is represented only by 
a single fragment of a lower jaw and various isolated teeth, and, 
although numerous portions of the skeleton are known, in but few 
cases have characteristic bones of the same individual been secured. 
Quite a number of generic names have been proposed for the 
remains found in England, and several are still in use, but the 
absence of the skull, and the fact that most of the type specimens 
pertain to different parts of the skeleton, render it difficult, if not 
impossible, to determine the forms described. 
In the large collections of Sauwropoda secured by the author in 
America, which include the remains of more than one hundred 
individuals, both the skull and skeleton are well represented. On 
this material, his classification of three families, Atlantosauride, 
Morosauride, and Diplodocide, has been based. The Pleurocelide, 
also, appear to be distinct, but the remains at present known are 
less numerous and characteristic than those pertaining to the other 
divisions of this group. 
In examining the European Sauropoda with some care, the author 
was soon impressed by three prominent features in the specimens 
investigated :— é 
1. The apparent absence of any characteristic remains of the 
Ailantosauride, which embrace the most gigantic of American forms. 
‘ Abstract of a paper read before Section ©, of the British Association for the 
Advancement of Science, at the Bath Meeting, Sept. 8th, 1888. 
