302 PALEONTOLOGY. 



Batrachians. Their teeth are conical, slightly curved, and 

 striated on the surface. Their microscopic character is 

 remarkable for the labyrinth-like arrangement of the 

 dentine, from whence Professor Owen derived the name 

 Jjabyrinthodon. The microscope has not, however, solved 

 the true position of the family ; for their dental structure 

 is equally removed from the crocodiles and the frogs. The 

 sinuous windings of the plates of dentine, seen in the 

 transverse section of the teeth, remind us of the structure 

 observed in some fishes ; but the circumstance of the teeth 

 having been found in sockets in the jaw prevents any mis- 

 conception as to the class to which they belong. "We know 

 five species of Labyrinthodon from the lower stage of the 

 new red-sandstone of England. 



The genera Mastodonsaurus, Capitosaurus, and Metopias, 

 are from the Keiiper, of Grermany. It is conjectured 

 that the foot-marks described as belonging to the genus 

 Cheirotherium, by Kaup, were imprinted by the genera of 

 this family. 



Third Order. OPHIDIA. Are characterised by their greatly 

 developed vertebral column, articulated by ball-and-socket 

 joints which give much mobility to the spine, by their 

 numerous ribs, loosely united cranial bones, and absence of a 

 sternum and extremities. (Eig. 205.) Ophidian remains are 



FIG. 206. FIG. 207. 



rare in a fossil state. An extinct genus Palaophis has been 

 found in the clay of Sheppey, and vertebrae (fig. 206 and 207), 

 probably belonging to the same, were found in the sands of 

 Bracklesham, and in the eocene sand of Kyson, in Suffolk. 

 The eocene stage of Brussels contains a fossil species of Cro- 

 talus ; and a species of Coluber and of OpJiis are found in the 

 sub-apennine stages of Europe. These Ophidian remains con- 

 firm the inference already drawn from the presence of tropical 

 genera of Mollusca, Chelonia, and Sauria, in the eocene ter- 



