HO THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



parietals. The sutures separating the frontal and parietal elements from each other 

 in the median line are of the zigzag form so characteristic of the labyrinthodonts. 



MEASUREMENTS OF THE TYPE OF ERPETOSAURUS TUBERCULATUS MOODIE. 



mm. 



Length of portion of skull preserved 52 Maximum width of parietal 1 1 



Width across tabulare (estimated) 60 Length of frontal 22 



Length of parietal 15 Width of frontal 12 



Genus ODONTERPETON Moodie. 

 MOODIE, Proc. U. S. Nat. Mus., 37, p. 19, 1909. 



Type: Odonterpeton triangularis Moodie. 



The generic characters may be found in the triangular shape of the skull, the 

 large size of the teeth, the shape of the vertebrae, the small size of the orbits, and 

 their anterior position as shown in the type specimen (fig. 22, E). The name of the 

 genus is derived from the remarkable size of the teeth as compared with the size 

 of the skull. 



Odonterpeton triangularis Moodie. 

 MOODIE, Proc. U. S. Nat. Mus., 37, p. 19, pi. 6, fig. 3, 1909. 



Type: Specimen No. 4465, U. S. National Museum. 



Horizon and locality: Linton, Ohio, Coal Measures. 



The specimen described under the above name is a representative of the small- 

 est species of the Microsauria so far described from North America. Orthocosta 

 microscopica Fritsch, from the Carboniferous of Bohemia, is a rival of the present 

 form in size, but the form described by Fritsch is an entirely different animal and 

 was formerly included among the so-called Aistopoda, which are regarded by the 

 writer as merely specialized microsaurians. The present form shows clear affinities 

 with the Microsauria. 



As may be seen by referring to the list of measurements, the skull of this form 

 measures only 6.5 mm. in length. The form may possibly be larval, though I do 

 not think so, if I may judge from the well-developed condition of the skull bones 

 and the complete ossification of the vertebrae. The sides of the skull are equal and 

 the occiput is a straight table, so that the skull forms almost an exact equilateral 

 triangle. The orbits are very small and are placed well forward. The interorbital 

 space is four times that of the diameter of the orbit, a very unusual character and 

 in itself worthy of ranking as a generic character. The median suture of the skull 

 is zigzag and incloses the minute parietal foramen near the posterior end of the 

 skull. The relations of the elements of the skull, with the exceptions of those of 

 the frontals and parietals, can not be determined with accuracy, although there are 

 here and there indications of sutures. The characters of the cranial elements, so 

 far as they can be determined, are those of the family Tuditanidae, and the form 

 may, for the present, be regarded as a member of that group. The teeth are very 

 long, slender, and sharp, and are placed close together. There is no indication of 

 fluting on the teeth. They are slightly curved inward. 



There are 13 vertebras present. The centra are hour-glass shaped, and are 

 apparently phyllospondylous, with the notochord largely persistent. The vertebral 



