128 



THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



as usual, formed by the squamosal. The orbit is bounded posteriorly by the post- 

 orbital and the postfrontal, which include in the angle between them the quad- 

 rangular squamosal. The orbit 

 is especially remarkable for its 

 size as compared with the dimen- 

 sions of the skull, being without 

 a parallel among other known 

 Microsauria. Around the border 

 of the orbit in the specimen Cope 

 studied (105) there were found 

 14 quadrangular plates which 

 he called "superciliary plates." 

 Hay (316) was inclined to regard 

 them as sclerotic plates. In the 

 Yale Museum specimen (plate 4, 

 figs- 5 6) there are 20- of these 

 plates, and there seems to be no 

 doubt that they are sclerotic ele- 

 ments. In the restoration (fig. 26) 

 29 sclerotic plates are given, but 

 there is no assurance that this 

 number is the exact one. They 

 may also have been slightly larger, 

 but not as large as in Branchio- 

 saurus. 



The vertebral column is pre- 

 served nearly entire in the Daniels 

 specimen and quite entire (478) 

 in the Yale specimen. Cope, in 

 his study of the type (105, 107), 

 thought there could be no more 

 than 13 presacrals, but the speci- 

 men was poorly preserved and in- 

 decisive on this point. Dr. Hay 

 (316) was inclined to the opinion 

 that there were less than 20. The 

 Yale specimen shows 22 centra, 

 which are elongate, hour-glass- 

 shaped bodies, with the neural 

 spine a long, low crest running 

 the entire length of the centrum, 

 with a median elevation, so that in lateral view the spine would be triangular in form. 

 The body of the centrum is expanded laterally into a diapophysis which extends 

 anteriorly. The posterior vertebrae, at least, had the notochord largely persistent. 



FIG. 26. Restoration of body outline and skeleton of Amphibamus 

 grandiceps Cope, from Mazon Creek, Illinois, shales. Restora- 

 tion is based on complete specimens of the species and on Cope's 

 drawing. Form of body is indicated in one specimen, that in 

 possession of Mr. Daniels. X 1.5. 



Skull: pmx, premaxilla; n, nasal ;fr, frontal; par, parietal; la, lac- 

 rimal; pf, pref rental; pof, postfrontal; po, postorbital; pp, post- 

 parietal; spt, supratemporal ; mx, maxilla; j, jugal; qj, quadrato- 

 jugal; sq, squamosal; tab, tabulare. 



Skeleton: ic, interclavicle ; cl, clavicle; sc, scapula; A.humerus; r-u, 

 radius, ulna; c, carpus; pu, pubis; il, ilium; /, femur; /, tibia; 

 fb, fibula; ts, tarsus; x, ischium. 



