492 



PROCEEDINGS OF TEE NATIONAL MUSEUM. 



VOL. 39, 



MANDIBLE. 



It has been possible to study both sides of the mandible. The left 

 ]amus was preserved in the coal with its inner face exposed. This 

 face is broken by two large oval openings, the internal mandibular 



foramina. Tliis is the term used by Rey- 

 nolds "• for the openings on the inner sur- 

 face of the alligator jaw. A drawing of 

 the jaw of the crocodile is introduced in 

 figure 4 for a direct comparison with the 

 present mandible. So far as I can ascer- 

 tain, no other known labyrinthodont man- 

 dible displays this character in such a 

 marked degree. Doctor Branson has fig- 

 ured in Anascliisma hrowni from the Trias- 

 sic of Wyoming the inner surface of the 

 right ramus on which there are Hkewise 

 two openings but differently situated.'' A 

 similarity between the two mandibles is observed in that the suture 

 separating the prearticular and angular touches the posterior edge of 

 the posterior foramen. 



Several of the sutures are well preserved and they have been indi- 

 cated in the drawing (fig. 2). The pillar separating the two fora- 

 mina is cut by the suture separating the angular and prearticular 

 very much as in Anascliisma, with the difference that in the latter 

 form the angular and prearticular are not approximated. I beUeve 



Fig. 1.— Portion of the skull of 

 Erpetosuchus kansensis Moodie. 

 Cat. No. 6699, U. S. N. M. Mx= 



MAXILLA, iV=NASAL. LATERAL LINE 

 CANAL REPRESENTED BY HEAVY 

 BROKEN LINE. 



Fig. 2.— Outer surface of left mandible of Erpetosuchus kansensis Moodie. Cat. No. 6680, 



U.S.N.M. ^=ANGULAR, ^r=ARTICULAR. OpERCULO-MANDIBULAR LATERAL LINE CANAL REPRESENTED 

 BY HEAVY BROKEN LINE. 



I detect the suture as represented separating the anterior end of the 

 angular from the dentary and splenial. I am assured of the portion 

 near the anterior foramen and also of the part near the tip of the 

 ramus. This shows the angular to be a very elongate element, run- 

 ning very nearly the entire length of the mandible, much as in 

 Anascliisma and other labyrinthodont genera. The splenial is a 



o Vertebrate Skeleton, p. 253. 



& Branson, Joum. Geol., vol. 13, no. 7, 1905, p. 589, fig. 10. 



