[Illustration: Fig. 26. Restoration of body outline and skeleton of _Amphibamus grandiceps_ Cope, from Mazon Creek, Illinois, shales. Restoration 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. × 1.5. Skull: _pmx_, premaxilla; _n_, nasal; _fr_, frontal; _par_, parietal; _la_, lacrimal; _pf_, prefrontal; _pof_, postfrontal; _po_, postorbital; _pp_, postparietal; _spt_, supratemporal; _mx_, maxilla; _j_, jugal; _qj_, quadratojugal; _sq_, squamosal; _tab_, tabulare. Skeleton: _ic_, interclavicle; _cl_, clavicle; _sc_, scapula; _h_, humerus; _r-u_, radius, ulna; _r_, carpus; _pu_, pubis; _il_, ilium; _f_, femur; _t_, tibia; _fb_, fibula; _ts_, tarsus; _x_, ischium. ] The vertebral column is preserved 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 specimen was poorly preserved and indecisive 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 vertebræ, at least, had the notochord largely persistent. The osseous part of the vertebra seems to have been but a thin shell, and the structure of the zygapophyses can not be determined. That they were dorsal in position is, however, evident from several vertebræ. The points of these structures project laterally. The tail is short and the caudal vertebræ weakly developed. There are distinct impressions of at least 12 pairs of ribs in the Daniels specimen. They are long, slender, and curved, and there is no definite assurance that there were as many ribs as are indicated (fig. 26) in the restoration (462). The ribs are intercentral (469) and probably occupied the full length of the vertebral column. There may have been as many as indicated in the restoration. One of the most interesting features of the Yale specimen is the preservation of a small patch of skin, evidently from the back, lying to one side near the head, measuring 5 mm. in length by 3 mm. in width. The fragment shows the skin to be of tuberculated scales, 4 of which occupy the length of 1 mm. The scales are somewhat hexagonal, almost rounded, and were relatively quite thick. They lie in a close mosaic (fig. 27). [Illustration: Fig. 27. Skeleton of _Amphibamus grandiceps_ Cope. × 1.4.