ThERIODONTS and JIIEIR ALLIES. 287 



forms. In 1889 he .sulj-divided the Thevomorpha. or Thernmora into 

 6 siili-iinU'is. Placixloiitia. Proganosauria. Parasiichia. Anomodonlia, 

 Peh cosaiiria. and Cotx losauria. 



In 1890 Lydekker in his Cataluijue of the Fossil Reptiles in the 

 ]"5ritish Museum made use of the term Anomodontia in i)racticaJly the 

 same sense as Co])e's Theromora. This large order he sub-divided 

 into the following sub-orders (1) Procolophonia. (2) Dicynodontia, 

 (3) Theriodontia. (4) Pareiasauria. This classification, though the 

 names are different, agrees fairly closely with Cope's. Lydekker omits 

 the Placodontia whose affinities are doubtful, and the Parasuchia 

 which he considers a distinct order, but his 2m\. 3rd and 4th sub- 

 orders agree with Cope s 4th. 5th and 6th. The onl\ difference with 

 regard to Procolophon is that while I.\<lekker places it in a sub- 

 order by itself. Cope unites with it its Palaeohatterian allies. 



In 1888 Seeley commenced his valuable series of " Resean hes 

 on ihe .Structure, Organisation, and Classification of the Fossil 

 Reptilia." which have not onl\ added greallv to our knowledge of 

 the structure of the Triassic reptiles, but have made us acquainted 

 with a number of new tvpes. in his first classification he (livide<l the 

 Anomodontia into 8 sul)-orders :— ( 1 ) Pareiasauria, (2) Procolophonia, 

 (3) Dicynodontia. (4) Gennetotheria, (5) Pelxcosauria, (6) Therio- 

 flontia. (7) Cot\ losauria. (8) Placodontia. The name Gennetotheria 

 was proposed for a grouj* to include l*ropaj)pus and Stereorhachis. 

 but was afterwards withdrawn. 



In 1895. as the result of his researches. Seelev advanced a much 

 more elaborate classification. The Anomodontia he divides into 

 two principal orders —Therosuchia and Therochelonia with possil)ly 

 a third. Alesosauria. The Therosuchia he again divides into (i) 

 Pareiasauria. including Procolophonia. (2) Gorgonojjsia, (3) Dinoce- 

 jihalia. (4) Deuterosauria including Placodontia, (5) Theriodontia, 

 including Lycosauria, Cynodontia. and Gomphodontia. (6) Endothio- 

 dontia. (7) ? Theromora. inckuiing Pehcosauria and Cotvlosauria. 

 The Therochelonia he stib-divides into the Dicynodontia and the 

 Ristecephalia. 



Though more elaborate this classification is much less satis- 

 factory than Seele\ s earlier one. So far as I am aware Seelev is 

 the only writer who has suggested any great division between the 

 Theriodonts ami the Dicynodonts. Owens first view of including 

 the Therioflonts in the same order as Dic\nodon was indeed much 

 nearer the taith. Though the specialisation of the Dicvnodonts 

 entitles them to be placed in a distinct order or sub-order, thev are 

 more nearly allied to Theriodonts such as (lalesaurus than are the 

 ))riniitive Theriodonts such as ^'F^lurosaurus or Ictidosuchus. 

 Deli>hinognathus. Tapinocephalus. Placodus. and even Deuterosaurus 

 and Rhopalodon are so imperfectlv known that it is impossif)le to 

 say at present with an\ degree of certainlv where the\ ought to be 

 placed, but the case is different with the Endf)thioflonts. Both 

 Owen and Lsdekker recognised the close affinit\ between 

 Kndothiodon and Dicynodon. and the considerable number of new 

 Endothiodont genera that have receiith been disct)vered |)rove that 



