Labyrinthodonts 69 



animals his study of fossils enabled him to assist in 

 bridging over the gaps between surviving groups of 

 creatures by study of creatures long extinct. He began 

 to study the structure of the L,ab3'rinthodonts, a group 

 of extinct monsters which received their name from the 

 peculiar structure of their teeth. He published elaborate 

 descriptions of Anthracosaurus from the coal-measures 

 of Northumberland, of IvOxomma from the lower car- 

 boniferous of Scotland, and of several small forms from 

 the coal-measures of Kilkenny, in Ireland, as well as 

 describing skulls from Africa and a number of frag- 

 mentary bones from dififerent localities. But in all this 

 work it was the morpholog}' of the creatures that inter- 

 ested him, and the light which their structure threw 

 upon the structure of each other and of their nearest 

 allies. He shewed that these monsters stood on the 

 borderland between fishes, amphibia, and reptiles, and 

 he added much to our knowledge of the true structure 

 of these great groups. Next, he turned to the extinct 

 reptiles of the Mesozoic age. It was generall}^ believed 

 that the Pterodactyls, or fij'ing reptiles, were the nearest 

 allies of birds, but Huxley insisted that the resemblances 

 between the wings were .simply such superficial resem- 

 blances as necessarily exist in organs adapted to the 

 same purpose. About the same time, Cope in America, 

 and Phillips and Huxley, in England, from study of 

 the bones of the Dinosaurs, another great group of ex- 

 tinct reptiles, declared that these were the nearest in 

 structure to birds. In association with the upright 

 posture, the ilium or great haunch-bone of birds ex- 

 tends far forwards in front of the articulation of the 

 thigh-bone, so that the pelvis in this region has a 

 T-shape, the ilium forming the cross-bar of the T, and 

 the femur or thigh-bone the downward limb. Huxley 



