THE AMERICAN 
33? 
Thertodont Characters. 
7. Separate transversum as in 
Reptilia and a distinct prevomer 
in certain types. 
8. Paired exoccipital condyles 
. with prominent median basioccipital 
element. 
g. Lower jaw composite, includ- 
ing dentary, articular, angular, and 
splenial. 
10. Cervical vertebrz with inter- 
centra. 
11. Cervical ribs separate, sutu- 
rally united with vertebræ. 
12. Anterior dorsal ribs interver- 
tebral in position with head intercen- 
tral and tubercle neurocentral. 
13. Scapular arch with clavicles 
and interclavicles; epicoracoid united 
by suture with the metacoracoid ; 
prescapular spines. 
14. Pelvic saint m AOS 
Forainen; acetabulum da peer 
bones secondarily develope 
15. Carpus and tarsus iinpertectty 
known. 
16. Humerus with powerful delto- 
pectoral crest, and entepi- and ecte- 
picondyles; entepicondylar foramen. 
NATURALIST. [VoL. XXXII. 
Promammatlian Characters. 
7. Transversum and prevomer 
missing. 
8. Paired condyles on exoccipi- 
tals only, with basioccipital element 
reduced. 
9. Lower jaw composed of a 
single bone. 
to. Cervicals and dorsals with 
embryonic intercentra in Insecti- 
vora. 
11. The same in monotremes and 
embryos of higher mammals. 
12. The same 
13. The same in monotremes ; 
clavicles and interclavicles wanting 
in higher types. Prescapular spines 
in monotremes. 
14. Pelvic arch with closed aceta- 
bulum, ischio-pubic symphysis, and 
large obturator foramen. 
15. Carpus with os-centrale; tar- 
sus with os-tibiale. 
16. The same in all basal Eocene 
mammals. 
Important, also, among the resemblances between the The- 
riodontia and Mammalia is the general body form, so far as it 
is known in the former, the proportions of the limbs to the 
back, and the apparent elevation of the body considerably above 
the ground. - This, taken together with the peculiar specializa- 
tion of the teeth into carnivorous and herbivorous types, indi- 
cates that the Theriodontia filled somewhat the same réle in 
the economy of nature as is filled by the Mammalia at the 
present time. 
The most striking general difference is the very 
large size of several of these animals, such as Cynognathus. 
