O. C. Marsh—On Dinosaurian Reptiles. 491 
These few facts will, I trust, throw some light on the affini- 
ties of the Reptiles known as the Dinosauria. The problein 
is certainly one of much difficulty, and I hope soon to discuss 
it more fully elsewhere. 
CLASSIFICATION OF DINOSAURS. 
In the present review of the Dinosaurs, I have confined 
myself mainly to the type specimens which I have described, 
but have included with them other important remains where 
these were available for investigation. The extensive collec- 
tions in the museum of Yale University contain so many of 
the important type specimens now known from America, that 
they alone furnish an admirable basis for classification, and it 
was upon these mainly that I first established the present sys- 
tem, which has since been found to hold equally good for the 
Dinosaurs discovered elsewhere. In the further study of 
these reptiles, it was also necessary. to examine both the 
European forms and those from other parts of the world, and 
I have now studied nearly every known specimen of impor- 
tance. These investigations have enabled me to make this 
classification more complete, and to bring it down to the 
present time. 
Many attempts have been made to classify the Dinosaurs, 
the first being that of Hermann von Meyer, in 1830. The 
name Dinosauria, proposed for the group by Owen, in 1839, 
has been generally accepted, although not without opposition. 
Heckel, Cope, and Huxley followed, the last in 1869 propos- 
ing the name Ornithoscelida for the order, and giving an 
admirable synopsis of what was then known of these strange 
Reptiles and their affinities. Since then, Hulke, Seeley, and 
Lydekker, Gaudry, Dollo, Baur, and many others, have added 
much to our knowledge of these interesting animals. Tlie 
remarkable discoveries in North America, however, have 
changed the whole subject, and in place of fragmentary speci- 
mens, many entire skeletons of Dinosaurian reptiles have been 
brought to light, and thus definite information has replaced 
uncertainty, and rendered a comprehensive classification for 
the first time possible. 
The system of classification I first proposed in 1881 has 
been very generally approved, but a few modifications have 
-been suggested by others that will doubtless be adopted. 
This will hardly be the case with several radical changes 
recently advocated, based mainly upon certain theories of the 
origin of Dinosaurs. At present these theories are not sup- 
ported by a sufficient number of facts to entitle them to the 
serious consideration of those who have made a careful study 
of these reptiles, especially the wonderful variety of forms 
recently made known from America. 
