FOSSIL REPTILES. 629 



better ossified than in Euparkeria. There are three large 

 elements and at least two small ones. The rest of the pes is 

 probably of the Rhynchocephalian type. 



There seem to have been no dermal ossifications in Mesosuchus. 



ScLEROMOCHLus TAYLORi Smith Woodward, 



One of the most remarkable of the double-arched reptiles from 

 the Elgin sandstone is the little form named by Dr. Smith- 

 y^ ooi\\\i\.v([ Scleromochlus iaylori. Though there are preserved in 

 the British Museum the remains of five individuals, and tliough 

 something is known of most of the skeleton, the animal is too 

 small to be well preserved in the coarse sandstone, and hence our 

 knowledge of the detailed structure is very imperfect. Smith 

 Woodward's description and restoi-ation give practically every- 

 thing one can be sure about. The skull seems to be essentially 

 similar to that of Ornlthosachus. 



Affinities of the Psetodosuchia. 



Mr. E. T. Newton, in describing Ornithosv,chus and Ilerjyeio- 

 suchtos, discusses the afl^inities of the forms. He calls attention to 

 the marked resemblances of the forms to Aetosaici^us, and even 

 thinks it possible — as we now know to be the fact — that Aetosaurus 

 has an infratemporal vacuity, and also discusses the relationships 

 with Stagonol&pis and others of the Parasuchia. A comparison is 

 also made with the Dinosaurs Com2)sognathus, A7ichisaurns, and 

 others, and with the skull resemblances in the Pberosaurian 

 Scyphognathus. In summing up the evidences he says : — "The 

 many points of resemblance between the Parasuchia and certain 

 of the forms usually included among the Dinosauria, have also 

 been noticed by other writers ; and the difficulty of sepai-ating 

 the two groups is increased by a study of this new Elgin reptile, 

 which holds, as I think, a more intermediate position between 

 the two series than any form hitherto described, for although the 

 characters of its skull and teeth find their nearest counterpart 

 among the Dinosaurs, and the pelvis and limbs might belong to 

 either a Theropodous Dinosaur, or a' Parasuchian, the form of 

 the free asti-agalus is more Crocodilian than Dinosaurian. While 

 acknowledging the difficulty of assigning this new reptile to either 

 of these groups, it seems most in accordance with the facts to 

 place it provisionally with the Dinosaurs." 



Mr. G. A. Boulenger, when describing the lai'ge specimen of 

 Oniithosioc/ms, ciiticises Newton's conclusions. He says : — 

 " Much as I admire Mr. Newton's description of Omithosiochus 

 .... I cannot .... endorse his conclusions as to the systematic 

 position of the reptile." " Dr. Smith A¥oodward was nearer the 

 truth when he compared it with Aetosaurus." Boiilenger argues 

 that Ornithosnchus should be placed with Belodov., Stagonolepis, 

 and Aetosaurus in the order named by Owen, Thccodontia — a 



42* 



