IO2 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



in fishes and amphibians. This subject has been fully treated in another place (458) 

 and it will only be necessary to state here that on the basis of the lateral-line canals 

 and their arrangement in fishes and the Amphibia the true correlation of the supra- 

 temporal elements in amphibians and fishes has been made. The temporal canal 

 in the present specimen has, apparently, an indication of a connection with the 

 supraorbital canal, but of this I am not sure. The jugal canal occurs on the supra- 

 temporal and quadratojugal, and it joins the infraorbital on the jugal. The infra- 

 orbital is indicated by a short portion a few millimeters long under the orbit and the 

 remainder, i.e., its connection with the jugal canal, is restored (fig. 22, G). There is, 

 nothing unusual to be observed in that portion of the infraorbital canal which is 

 preserved. The supraorbital canal is indicated by a curved, broad, shallow groove 

 on the inner side of each orbit. As stated above, there seems to be a connection 

 between this canal and the temporal, but I am not sure. The primitive conditions 

 shown in the lateral-line canals in Erpetosaurus tabulatus Cope are the presence of 

 the occipital cross-commissure and the ring-like formation of the temporal and 

 jugal canals, which is too clearly indicated to be overlooked. 



MEASUREMENTS OF THE TYPE OF ERPETOSAURUS TABULATUS COPE. 



Him. mm. 



Median length of skull 29 Diameter of nostril I 



Width of skull, posterior border, estimated 37 Diameter of pineal foramen i 



Width between tabulare angles 18 Length of right clavicle 13 



Length of orbit 8 Width of right clavicle S-5 



Width of orbit 6.5 



MANDIBLE PROVISIONALLY ASSOCIATED WITH ERPETOSAURUS TABULATUS COPE. 

 MOODIE, Bull. Amer. Mus. Nat. Hist., xxvi, pp. 351-352, pi. lix, fig. 2; pi. Ixiv, fig. 3, 1909. 



This specimen is preserved almost completely on a slab of soft coal. It is im- 

 possible to determine positively to what microsaurian species the mandible be- 

 longs, but it may, for the present, be associated with Erpetosaurus tabulatus Cope 

 on account of its size and the character of its sculpture. This is the first and almost 

 the only known example of a mandible of an American microsaurian. The form of 

 the jaw is perfectly preserved, although the condition of the articular surface can 

 not be determined. 



The proportions of the mandible, as may be judged from the table of measurements, 

 are rather stout and the teeth are strong and numerous. There are evidences of 19 

 teeth preserved. The sutures separating the articular (art) , angular (ang) , surangular 

 (so) , coronoid (cor) , and the dentary (d) (fig. 22, F) are clear for at least the greater part 

 of their length and they may be easily restored for the remainder of their course. 

 The surangular is thus seen to rival the dentary in size and on it occurs the peculiar 

 sculpturing which approximates so closely that on the skull of Erpetosaurus tabu- 

 latus Cope. The presence of the long anterior tooth is strikingly characteristic of 

 many Microsauria. It is well developed in Sauropleura longidentata Moodie and 

 Sauropleura (Anisodexis) enchodus Cope. It is also present in well-developed form 

 in the later labyrinthodonts. The teeth are all, with the exception of the fourth 

 from the anterior end, rather short, curved, and sharply pointed, with an indication 



