No. 377.] THE ORIGIN OF THE MAMMALIA. 325 
2. The Gomphodontta. 
All the remains of this group have been found in the upper 
Permian Beds of Ailwell North and Lady Frere, contemporary 
with the specialized theriodonts.. The geological position of 
Tritylodon is not certainly known, but the other gomphodont 
genera, Gomphognathus, Microgomphodon, Trirachodon, and 
Diademodon, are certainly located in these upper Karoo Beds, 
and are below the Stormberg Beds, which are considered 
Triassic. Seeley (1895, 4) confidently places these animals 
in the order Theriodontia (contrasting them with the carnivorous 
Cynodontia) as typical herbivorous forms with molar teeth flat- 
tened and expanded transversely and more or less tuberculate. 
crowns. The cranial and skeletal characters, so far as they are 
Fic. 1 Anter ht H fi j G showing 
parerii deltoid pios grda i ena foramen ; separate articular facets 
for radius and ulna. (4 natural size. After Seeley.) 
known, support Seeley’s conclusion, and the wide diversity in 
the structure of the teeth ddes not alone constitute a sufficient 
ground for the separation of these herbivorous forms from the 
carnivorous Theriodontia. If Tritylodon belongs to this group, 
