Professor Marsh’s Monograph of the Dinocerata. 201 
In figure 38, above, a diagram is given, which shows graphi- 
cally these lines of descent, and the most probable genealogy of 
modern ungulates.. The diagram, being on a plane, can only 
indicate the general position of these divergent lines. 
From this grap came off; evidently in the late Cretaceous, 
first the Coryphodontia, having nearly all the above characters, 
and becoming extinct in the early Eocene. 
The L/inocerata probably branched off about the same time, 
: jee thus becoming much more 
‘pecialized before their extinction. 
i “Accepting this general view of the origin of the Ungulates, 
ie and extinct, their classification has been outlined in the 
lagram on page 200. 
of The attempts hitherto made to give a detailed classification 
all the Mammalia, living and extinct, have signally failed, 
mainly because only a small part of even the extinct forms now 
re is to indicate the main groups and their affinities, 
ora future discoveries. 
xcluding the aberrant, aquatic, Sirenians, now regarded as 
own extinct forms, the ungulate mammals may then be 
‘ranged in natural groups, as follows : Y 
CLASS MAMMALIA. 
Sub-Class MoNopELPHIA. 
Super-Order UNGULATA, 
(1.) Order Hyracoidea. 
: (2.) Order Proboscidea. 
(3) 0 _ § Dinocerata. 
) Order Amblydactyla Coryphodontia. 
tion ¢ 
ch 
tageo 
thoy ..3: n¢ 
iy Indicate a genetic connection, Pade 98 remote, with the 
erent groups that share them. Special characters, on the 
