1 90 



HISTORICAL PALAEONTOLOGY. 



in character to those which occur in theTriassic 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. AU of them seem to have be- 

 longed to the division of Amphibians in which the long tail 

 of the young is permanently retained j 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 



Fig. 132. — a. Upper surface of the skull of Anihracosaurus Russelli, one-sixth of the 

 natural size ; b. Part of one of the teeth cut across, and highly magnified to show the 

 characteristic labyrinthine structure ; c. One of the integumentary shields or scales, one- 

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



two occipital condyles, and having its surface singularly pitted 

 and sculptured ; and tl>e vertebrae are hollowed out at both 

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

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

 and an extremely characteristic feature (from which the entire 

 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, h). Many of the 

 Carboniferous Labyrinthodonts are of no great size, some of 



