A DESCRIPTION OF THE GENUS DIMETRODON, COPE. 29 



Haeckel 39 in 1866 divides the Anomodontia into three families : 



1. Rhopalodonlia — Rhopalodon, Permian Russia. 



2. Dkynodontia — Dicynodon, Ptychognathus. 



3. Cryptodontia — Udenodon, Rhynchosaurus. 



The order Theriodontia was established by Owen 40 early in 1876. It was to contain 

 Galesaurus and Cynochampsa and the new South African genera Lycosaurus, Tigrisu- 

 chus, Cynosuchus, Nythosaurus, Scaloposaurus, Procolophon, Gorgonops, as well as the 

 genus Oynodraco. He remarks : 



" For the name of these extinct carnivorous Saurians I find it convenient and believe 

 it will be generally acceptable to form a distinct order of Reptilia under the denomina- 

 tion of Theriodontia, with the following characters : Dentition of the carnivorous type ; 

 incisors defined by position, and divided from the molars by a large laniariform canine 

 on each side of both upper and lower jaw, the lower canine crossing in front of the 

 upper ; no ectopterygoids ; humerus with an entepicondylar foramen ; digital formula of 

 fore foot 2, 3, 3, 3, 3 phalanges." 



In 1878 appeared Owen's Catalogue of the Fossil Reptilia of South Africa. 41 The 

 Order Theriodontia is now defined in the following way : 



" Char. Dentition of the carnivorous type ; incisors defined by position, and divided 

 from molars by a large laniariform canine on each side of both upper and lower jaws, 

 the lower canine crossing in front of the upper as in Mammalia." 



The Theriodontia are divided in three sections. 



Section Binarialia. 



The external nostrils are divided by a narrow partition ; the entire skull has a com- 

 pressed form. 



Genera Lycosaurus Ow. Species L. pardalis Ow., L. tigrinus Ow., and L. curvimola Ow, 

 Tigrisuchus Ow. Species T. simus Ow. 



Fam. Mononarialia. 



In this family of Theriodontia the external nostril is single or undivided, and the 

 incisors exceed three in number in each premaxillary. 



Genera Cynodracon Ow. Species C. serridens Ow., G. major Ow. 

 Cynochampsa Ow. Species C. laniarius Ow. 

 Cynosuchus Ow. Species C. suppostus Ow. 

 Galesaurus Ow. Species G. planiceps Ow. 

 Nythosaurus Ow. Species N. larvatus Ow. 

 Scaloposaurus Ow. Species 8. constrictus Ow. 

 Procolophon Ow. Species P. trigoniceps Ow., P. minor Ow. 



