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D. M. S. Watson — The Cheirotheriutn. 



The groups of animals known, by the discovery of their bones, 

 to have been in existence in Europe during the time of the Cheiro- 

 therium are — 



1. The Stereospondylous Stegocephalia. The limbs of these 

 amphibia are extremely imperfectly known, but the materials of 

 Mastodonsaurus and Mdoposaurus show that, like all the Permian 

 Stegocephalia, they had very short legs, the humerus and femur being 

 carried at right angles to the body and the track necessarily very 

 wide. The apparent rarity of caudal vertebrae suggests that the tail 



Fig. 1. — Footprints of Cheirotherium. 



was short. Furthermore, it is rend(^red probable by the enormous 

 size of the head, which must have carried the centre of gravity very 

 far forward, that the fore-feet were larger than the hind.^ They can 

 therefore have had nothing to do with Cheirotherium. 



■^ The Stuttgart material of Mastodonsaurus, when examined in the light of 

 the now well-known Eryops, shows clearly that Dr. Fraas's familiar restoration 

 of the pelvis is quite wrong; his 'ilium', as shown conclusively by the 

 occurrence of a specimen lacking the pubis, and of an isolated ischium, is 

 really the whole os innominatum, nearly identical with that of Eryops. 

 Dr. Fraas's pubis is an ischium, and his ischium a scapula-coracoid extremely 

 similar to that of Eryops. There is also a humerus, figured by Pleininger 

 many years ago, which, except that it is rather more slender, perfectly 

 resembles that of Eryops. 



