l8o THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



The ventral surface of the pleurocentrum bears a structure, which is, without 

 doubt, a chevron, although the character of its opening can not be determined. It 

 is elongated and is united by a broad base to the pleurocentrum. Its union is by a 

 clearly defined suture, which is apparent in 3 vertebrae. The condition represented 

 by the specimen duplicates almost exactly the condition figured by Cope for the 

 caudal region of Cricotus Cope.* 



The intercentrum of the present form is fully as large as the pleurocentrum. 

 The significance of this has already been mentioned. The body of the centrum is 

 pierced by a large notochordal canal. 



Measurements of the Type of Spondyi.erpeton spinatum Moodie. 



mm. mm. 



length of specimen 60 Height of intercentrum 10.5 



Length of pleurocentrum 1 1 .5 Height of chevron 3 



Height of pleurocentrum to base of neurocentrum . 20 Length of chevron 18 



Length ot neurocentrum 33 Width of notochordal opening in centrum 5 



Width of neurocentrum at base 9 Height of same 4.5 



Width across anterior zygapophysis 12 Height of neural canal 12 



Width across posterior zygapophysis 10 Greatest width of neural canal 6 



Length of intercentrum 10 



Family ERYOPID.ffi Cope, 1882. 

 Cope, Am. Nat., .\vi, p. 334, 1882. 



Large, terrestrial or amphibious vcrtebrata; skull bones deeply marked with 

 pits and grooves which take the form of lateral-line canals; infra- and supra- 

 orbital canals, antorbital commissure, jugal canal, and occipital cross-commissure 

 of the lateral-line system present in Eryops megacephalus Cope ; carpus and tarsus 

 osseous; pubis an osseous plate, surrounded in life by a large amotmt of cartilage; 

 fore and hind limbs pentadactyl ; orbits, in the typical genus, located far back on 

 the skull and near the median line; cleithnmi present on the scapula; vertebrae 

 rachitomous, the intercentnmi supporting the arch in the dorsal region ; para- 

 sphenoid well-developed or reduced; teeth on pterygoids, palatines, prevomers, 

 and parasphenoid. 



Range: Uppef Pennsylvanian to Permian. 

 Distribution: America, Europe, Asia. 



Genus ERYOPS Cope, 1877. 



Type: Eryops megacephalus Cope. 



Skull long, comparatively narrow; proportion of length to breadth about 9 

 to 7. Roof bones coarsely sculptured posteriorly, finely sculptured anteriorly. 

 Nasals and premaxilla; very large; f rentals excluded from the orbits by junction 

 of pre- and post-frontals. Pterygoids not meeting in the median line; parasphe- 

 noid dagger-shaped, tapering gradually to a point just in front of the palatine 

 foramen ; prevomers large. Orbits subcircular, situated in the posterior half of the 

 sktiU; nares subovate, remote, at a considerable distance from the tip of the skull. 

 Many minute denticles, on pterygoids, palatines, prevomers, and parasphenoid. 

 Teeth circular in cross-section, strongly ribbed near the base, dentine strongly 

 infolded. Three large teeth on each palatine. Mandible without postcotyloid 

 process. Vertebras rachitomous. Ribs double-headed. Pubis osseous. Three 

 species (Permian), E. megacephalus, E. lalus, and E. willisloni, are assigned to 

 the genus. 



Eryops is represented in the Carboniferous deposits of North America by incom- 

 plete vertebral remains described by Case (94) from near Pittsburgh, Pennsylvania. 



• Cope, E. D., Trans. Am. Phil. Soc., xvi, p. 246, 1890. 



