192 BRITISH FOSSIL REPTILES. 



figs. 8 and 9. The conformity of this cliaracter with that shown in the preserved 

 portion of the upper jaw will be appreciated by the side-view of that portion 

 introduced in fig. 7 of Plate 4. In the vacant mandibular sockets, corresponding 

 to the upper teeth in place, are germs of successioual teeth, more or less advanced 

 in formation. The number of sockets in the single alveolar series is not less than 

 fifty : to which add a much larger canine or tusk at the inflected symphysial end. 

 A Batrachian mandibular character is exaggerated in Labyrinthodon by the 

 extension of the angular element of the jaw along the under part of the ramus 

 to the short symphysis. The ' harmonia,' or toothless suture indenting the outer 

 surface, indicates the proportions of the angular and dentary elements contributed 

 to that surface. Figures of the best preserved maxillary and mandibular seinal 

 teeth, slightly magnified, are given in advance of the views, natural size, of the 

 upper and lower jaws of Labyrinthodon leptognathus. 



Labyrinthodon pachygyiathus, Owen. (Batrachla, Plates 3 and 4-.) 



The portions of upper jaw on which this species is founded are represented 

 of the natural size in figures 4, 5, 9, and 10 of Plate 3. The outer surface of the 

 portion preserved of the maxillary shows the characteristic coarse sculpturing ; 

 part of the vomerine nostril is indicated at c, figs. 9 and 10. The alveolar and 

 part of the palatal processes of the maxillary afford the subjects of figs. 4 and 5 ; 

 and the crown of the best preserved maxillary tooth is represented in fig. 6. 

 Figs. 7 and 8 are portions of a mandible, but the characters of this bone and of 

 its teeth are exemplified in figs. 1, 2, 3 of Batrachla, Plate 4, from parts of the 

 right ramus. 



The outer surface of the dentary is traversed by a longitudinal groove midway 

 between the upper and lower borders, indicative of the proportions of the dentary 

 and angular elements thereto contributed. The part of the outer surface of the 

 angular in the hinder portion of the mandible of Lab. pachygnathus is broken 

 away. On the inner surface of the fore part of the ramus (fig. 2) is shown the 

 pointed termination of the splenial element, which extends to near the symphysis ; 

 an upper view of the same fore end of the ramus is given in fig. 3. The 

 mandibular dentition is instructively shown in the present specimens. The small 

 serial teeth exhibited more or less entire, or indicated by sockets, in the two 

 portions of jaw, are not fewer than forty. The symphysial end of the ramus 

 supports two much larger tusk-like teeth, with indication of a third of less size, 

 but exceeding that of the serial teeth. Of these the crown is best preserved in the 

 posterior portion of the ramus (fig. 1 ) , which had been detached from the rest. The 



