CHAPTER XXV. 



THE STEREOSPONDYLOUS AMPHIBIA FROM THE COAL MEASURES 



OF NORTH AMERICA. 



DEFINITION OF THE ORDER STEREOSPONDYLIA ZITTEL, 1887. 

 ZirrEL, Handbuch der Paleontologie, BJ. iii, Abth. i, p. 397, 1887. 



Large terrestrial vertebrates; largest of the class. Skull equal to one-fourth 

 or one-third of the entire body in at least one species, Metoposaurus diagnosticus 

 von Meyer (242). Lateral-line canals always present (458) on the skulls as deeply 

 impressed grooves which, in life, were possibly roofed over by a cartilaginous or 

 other connective-tissue membrane. The sensory organs undoubtedly being sup- 

 plied by the superficial ophthalmic branch of the trigeminal nerve, branches of 

 which pierced the cranial elements near the grooves, no evidence of such openings 

 in the bottoms of the grooves; the condition probably being analogous to Hydrola- 

 gus colei and other chimaeroids. Vertebra; stereospondylous, with well-developed 

 neural arches from which projected the well-developed zygapophyses, sometimes 

 slightly amphicoelous and pierced for the notochord, such forms being uncertainly 

 placed in the group. Tail unknown, possibly short. Limbs and girdles well 

 developed (243), phalangeal formula unknown; carpus osseous and tarsus un- 

 known. Pectoral girdle composed of osseous scapulae, clavicles, interclavicle, 

 coracoid ( ?) ; clavicles and interclavicle ventrally sculptured. Pelvic girdle com- 

 posed of osseous pubis, ischium, and ilium (242), the pubis a small plate, in life 

 largely cartilaginous, the three uniting by cartilaginous vmion to form the acetabu- 

 lum. Ventral armature unknown, possibly wanting. 



Range: Pennsylvanian to Upper Triassic. 



Distribution: North America, Europe, Asia, Africa, and Australia. 



Family MASTODONSAURrD.« Huxley, 1863. 



Huxley, Quart. Jour. Geol. Soc., xi.x, p. 65, 1863. 



Lydekker, R., Cat. Fossil Reptilia Amphibia, pt. iv, p. 141, 1890. 



Skull triangular, and more or less elongated, with the cranial bones very 

 strongly sculptured, the occipital condyles ossified (49), and large palatal vacuities; 

 dentine of teeth with very complex plications (502); no bony rings (242) in scle- 

 rotic; and no ventral scutes. Bodies of vertebrae (49) fully ossified in the adult. 

 There are large palato-vomerine tusks on the inner side of the maxillary teeth; 

 and the palatines run parallel to the maxilla. The mandible has a large post- 

 articular process; and there is a small inner series of mandibular teeth. In the 

 type genus the pubes are separate from the ischia, and do not enter into the 

 formation of the acetabulum; and the sacral ribs form kidney-shaped disks (393). 



Represented in North America by a single tooth from the Carboniferous of 

 Kansas. Described by Williston as Mastodonsaurus sp. (Kans. Univ. Quart., vi, pp. 

 209-210, pi. xxi). Represented in the Triassic of Wyoming by Anaschisma browni, 

 Branson (49). 



Mastodonsaurus sp. indet. 

 WaLisTON, Kans. Univ. Quart., vi, p. 209, 1897. 



The specimen preserved comprises the entire crown of a single vomerine (?) 



tooth, 38 mm. in length by 14 mm. indiameteratba.se (pl.2i,fig. 6). The immediate 



tip had been partly worn away in life, but was acuminate. It is composed of a dense 



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