PEDIGREES AND RELATIONSHIPS 19 



mentioned Palceohatteria of the Lower Permian of Saxony, a 

 long-tailed reptile of about a foot and a half in length, and the 

 aforesaid Protorosaurus of the Upper Permian of Thuringia and 

 Durham which attained a length of between four and five feet. 

 These are the earliest and most primitive types. More nearly 

 allied to Sphenodoti is Rhynchosaurus of the Upper Trias, or 

 Keuper, of Shropshire and Warwickshire, and Hyperodapedon, 

 with its pavement-like series of upper teeth, from the Upper 

 Trias of both England and India. Much nearer to the living 

 type is Homccosaurus of the Upper Jurassic of the Continent ; 

 while in the Upper Cretaceous the group is represented by the 

 long-snouted Ckampsosaurus. Very interesting is Proterosuchus 

 of the South African Trias, which appears to be a rhyncho- 

 cephalian showing a considerable degree of specialisation along 

 the line which gave rise to the crocodiles. 



Very few words must suffice for the Pelycosauria, a group 

 of chiefly North x-\merica Permian reptiles, whose affinity seems 

 to be with the Rhynchocephalia, from which they apparently 

 form a side-branch. They have frequently been confounded 

 with the theriodont anomodonts, to which they assimilate in 

 their dentition. The quadrate-bone is remarkably small and 

 surrounded by the adjacent elements ; and in the typical forms, 

 such as Naosaurus, the spines of the dorsal vertebra;, as will be 

 more fully noted in the sequel, are enormously elongated. The 

 dentition is thecodont. 



Next in the direct line of descent from the rhynchocepha- 

 lians may be placed the Upper Triassic belodonts, or Para- 

 suchia (sometimes, although incorrectly, termed Thecodontia). 

 These reptiles, as typified by Phytosanrus (or Be/odon), are fre- 

 quently classed with the crocodiles, with which they agree in 

 having the teeth set in distinct sockets, and in possessing a 

 pitted dermal bony armour ; the teeth, as in crocodiles, having 

 hollow roots in which the germs of their successors are deve- 

 loped, like a " nest " of thimbles. As a matter of fact, the 

 belodonts appear to be equally nearly related to a number of 

 others. They resemble, for instance, pelycosaurians, typical 

 dinosaurs, and crocodiles in their socketed teeth ; and thereby 

 differ markedly from rhynchocephalians. On the other hand, 

 they agree with the latter group and with pelycosaurians, and 

 differ from crocodiles and dinosaurs in the retention of distinct 



