Prof. Owen on the Labyrinthodon and Cheirolherium. 401 



lar cavity with that of a crocodile twenty-five feet in length, then 

 the hinder extremities of the Labyrinthodon must have been of dis- 

 proportionate magnitude compared with those of existing Saurians, 

 but of approximate magnitude with some of the living anourous 

 Batrachia. That such a reptile, of a size equal to that of the reptile 

 whose remains have just been described, existed at the period of the 

 new red sandstone, Mr. Owen says, is abundantly manifested by the 

 remains of those singular impressions to which the term Cheirothe- 

 rium has been applied. Other impressions, as those of the Cheiro- 

 therium Hercules, correspond in size with the remains of the Laby- 

 rinthodon Salamandroides, which have been discovered at Guy's 

 Cliff. The head of' a femur from the same quarry in which the 

 ilium was found, is shown to correspond in size with the articular 

 cavity of the acetabulum. The two toe-bones, or terminal phalanges, 

 are stated to be strictly Batrachian, presenting no trace of a nail, and 

 from their size are referred to the hind-feet of the L. pachygnathus. 



Thus, observes Mr. Owen, all these osseous remains from the 

 Warwick and Leamington sandstones agree in their essentially Ba- 

 trachian nature, and, in this interesting conclusion, with the fossils 

 of the German keuper ; and he concludes this portion of the memoir 

 with some observations respecting the so-called Cheirotherium foot- 

 steps. He has long believed that they were the foot-prints of a Ba- 

 trachian, and most probably of that family which includes the toad 

 and frog, on account of the difference of size in the fore and hind ex- 

 tremities ; but, in consequence of the peculiarities of the impressions, 

 he has always considered that the animal must have been quite 

 distinct in the form of its feet from any known Batrachian or other 

 reptile. Now then, he observes, we have in the Labyrinthodon 

 also a Batrachian reptile, differing as remarkably from all known Ba- 

 trachia and from every other reptile in the structure of its teeth : both 

 the footsteps and the fossils are, moreover, peculiar to the new red 

 sandstone ; and though the generic name Labyrinthodon may be 

 susceptible hereafter of being expanded to the appellation of a family, 

 yet, he asks, rogy it not be justifiable to consider the term Cheiro- 

 therium as one of the synonyms of Labyrinthodon ? 



Labyrinthodon scutulatus. — The remains, to which this specific 

 designation has been applied by the author, composed a closely 

 and irregularly aggregated group of bones imbedded in sandstone, 

 and manifestly belonging to the same skeleton ; they consist of four 

 vertebra, portions of ribs, a humerus, a femur, two tibia?, one end 

 of a large flat bone, and several small osseous, dermal scuta. The 

 mass was discovered in the new red sandstone at Leamington, and 

 was transmitted to Mr. Owen by Dr. Lloyd in the summer of 1840. 



The vertebrae present biconcave articular surfaces similar to those 

 of the other species. In two of them, the surfaces slope in a parallel 

 direction obliquely from the axis of the vertebrae, as in the dorsal 

 vertebrae of the frog, indicating an habitual inflexion of the spine, 

 analogous to that in the humped back of the frog. The neurapo- 

 physes are anchylosed to the vertebral body. The spinous process 

 rises from the whole length of the middle line of the neurapophysial 



Phil. Mag. S. 3. Vol. 19. No. 125. Nov. 1841. 2D 



