COAL- MEASURE STEOOCEPHALIAX. 



953 



The premaxilla appears to bear three teeth, but the suture 

 separating it fi-om the maxilla with six teeth is not quite certain. 



Text-fi^. 164. 



Lflc. Fr. Rj.R,, 



JBatracJiiderpeton lineatum. Left lateral aspect of the restored skull and clavicular 

 apparatus. Skull from specimen II., clavicle, etc., from specimen III. XI. 



Reference letters as in former figures with : — Jr., Jugal ; Qu.Ju., Quadrato-jugal. 



Lower Jaw. — Material. 



Specimen III. The perfect left ramus and disarticulated parts 

 of the right ramus of the same individual. Although the 

 posterior part of the right ramus, composed of the angula)-, 

 surangular, and preaiticular, is not well preserved, this specimen 

 is of great importance becavise it gives the most satisfactory 

 evidence of the front of the mandible, the dentary and splenial 

 being slightly separated and completely free from matrix on 

 the outer and largely so on the inner side. 



Specimen V. A perfect right ramus showing well the suture 

 between the prearticular and the angular. (Atthey collection.) 



Specimen VI. A perfect right ramus. (Barkas collection.) 



Specimen VII. An isolated dentary. (Atthey collection.) 



The various specimens are crushed in different dii-ections and 

 suggest that the jaw had a considerable cavity and was perhaps 

 nearly circular in cross section. 



There is a distinct though short postarticular process. 



The articular is well ossified though small ; it bears an articular 

 facet adapted to the trochlea qviadrati. 



The suture between the sui-angular and angular is not clearly 

 shown in any specimen. The angular is a very large bone 

 extending nearly up to the symphysis ; it forms the lower part 

 of the jaw, and its inner border articulates by a suture (spe- 

 cimen V.) with the pi-earticular, from which it is separated by 

 a small oval internal mandibular vacuity. 



The prearticular is a large bone covering the inner side of the 

 articular and extending well forward. 



The dentary is a fairly large bone overlapping the surangular 

 and angular behind ; it bears eleven or twelve swollen teeth and 

 has a symphysis with its fellow ; its lower border has a suture 



