194 



HISTORICAL PALEONTOLOGY. 



been recognized by their curious hand-shaped footprints, similar 

 in character to those which occur in the Triassic rocks, and which 

 will be subsequently spoken of under the name of Cheirotherium. 

 In the Coal-measures of Britain, the continent of Europe, and 

 North America, however, many bones of these animals have 

 been found, and we are now tolerably well acquainted with a 

 considerable number of forms. All of them seem to have be- 

 longed to the division of Amphibians in which the long tail 

 of the young is permanently retained ; and there is evidence 

 that some of them kept the gills also throughout life. The 

 skull is of the characteristic Amphibian type (fig. 132, a), with 

 two occipital condyles, and having its surface singularly pitted 

 and sculptured; and the vertebrae are hollowed out at both 

 ends. The lower surface of the body was defended by an 

 armor of singular integumentary shields or scales (fig. 132, c) ; 

 and an extremely characteristic feature (from which the entire 



fi 7 a ; ^ PC f rS ^ e * tbeskullof A nthracosaurua RusselU, one-sixth of the 

 , H ; S ^ ?L ne of the teeth cut across ' and hi ^ hl y magnified to show the 

 hf nfV ^ J 11 ? 6 8t cture 5 c > of the integumentary shields or scales, 

 le-half of the natural size. Coal-measures, Northumberland. (After Atthey.) 



group derives its name) is, that the walls of the teeth are deeply 

 folded, so as to give rise to an extraordinary "labyrinthine" 

 pattern when they are cut across (fig. 132, b). Many of the 



