MORPHOLOGICAL REVISION OF THE SUBORDER. 151 



The pelvis is represented by both ilia, parts of the pubes and a fragment of the 



ischium. 



The ilium has the same form as that of N. daviger ; the upper end is flared and 

 marked by radiating rugose ridges at the extremity. The pubis and ischium are so 

 incompletely preserved that they can not be perfectly characterized, but in general 

 they have the same form as A^. daviger. 



The hind limb is unknown. 



No. 4060 American Museum. 

 Seventh cervical : 



Measurements. 



mm. mm. 



Length, spine of 15th vertebra 812 



Heighrof TpTne above posterior zygapophyses 4 1 ^ ^'°f 6V^°e'rt°ebra°^ °^~ 43 



Antero-posterior diameter of spine : 17th vertebra.'.".' .'.■ .■.'.■ 43 



At hrst processes 18 jsth vertebra 45 



Atapex 3a igthvertebra 39 



Eighth vertebra : 20th vertebra 4° 



Length of centrum 34 21st vertebra 40 



Height of spine from bottom of centrum.. . 520 ^2(1 vertebra 34 



Ninth %'ertebra (first dorsal): 23d vertebra 29 



Length of spine from bottom of centrum. . . 578 24th vertebra 25 



Eleventh vertebra (dorsal) : Vertical diameter of ilium 14° 



Length of spine from bottom of centrum . . . 707 Total length of clavicle 158 



Length, bottom line of centrum of— Total length of scapula (exclusive of coracoid) . . 165 



13th vertebra 39 No. 4037 American Museum. 



15th vertebra 40 Length of humerus 217 



EDAPHOSAURIDAE Cope. 

 Edaphosaurus pogonias Cope (plate 34). 



Characteristic specimen. No. 4009 Am. Mus. The type. 



This specimen is unique, nothing identifiable with it occurring in either the 

 New York or the Chicago collections. The depressed form of the skull and the sug- 

 gestion of the axis that the vertebra were low and broad indicates affinities with the 

 Cotylosaitria, but the temporal region with its enonnous superior temporal vacuity 

 and almost certain inferior vacuity indicates affinities with the Pelycosaitria. As the 

 condition of the temporal arches is of more fundamental importance than that of the 

 shape of the skull and the vertebrae the animal is referred tentatively to the Pelycosauria 

 in the family Edaphosaiiridcc. Its habits of life must have been ver>' similar to those 

 of Placodiis, and if future discoveries should show that it really possessed a single 

 temporal vacuity, or that the inferior vacuity was decadent, the kinship of Edapho- 

 saurus with Placodus as an ancestral form would be strongly suggested. 



The skull is roundly triangular and flattened above; the temporal region is ele- 

 vated and the upper surface descends in an almost straight line to the anterior end. 

 The external nares are small and nearly terminal, but open laterally. The orbits are 

 of moderate size and look nearly straight outwards. The dentition is very peculiar, 

 varying from chisel-shaped incisors to thin, triangular cutting teeth in the anterior 

 portion of the maxillary and conical teeth in its posterior portion. 



The premaxillary is short and relatively broad, but with a long posterior prolon- 

 gation in the median line which extends back to join the nasals. There are four 



