1032 CLASS AMPHIBIA. 



represented by Gondwanosaurus ; while, if we may judge by a 

 detached intercentrum which may belong to it, Rhytidosteus, of the 

 Karoo system of South Africa, should also find a place here. The 

 American Permian, in addition to T rimer or hachis, has also yielded 

 Zatrachys, Eryops, Acheloma, and Anisodexis. Eryops includes very 

 large species, in which the nares are widely separated and not 

 placed at the extremity of the snout, and the thoracic plates are 

 not sculptured. 



Family Diplospondylid^e. — This family 1 is proposed by Dr 

 Fritsch for the genus Dip/ospondy/us, from the Permian of Bohemia, 

 characterised by the embolomerous structure of the entire verte- 

 bral column, and the absence of pits on the skull. Cricotus (fig. 

 961), from the Permian of Illinois and Texas, appears to be an 

 allied form, which Professor Cope makes the type of the family 

 CricotidcB. 



Finally, it may be mentioned here that the genus Ichthy acanthus, 

 from the Carboniferous of Ohio, which is frequently placed in the 

 Microsauria, is described as having rhachitomous vertebrae. 



Family Nyraniid/e. — The genus Nyrania, from the Permian of 

 Bohemia, of which the skull is shown on an enlarged scale in figs. 

 824, 825 (pp. 902, 903), differs from Archegosaurus in that the pala- 

 tines, in place of forming splints on the inner side of the maxillae, 

 are situated near the middle line, internally to the vomers and 

 pterygoids, and would therefore seem to represent a distinct family. 

 This arrangement of the bones of the palate is similar to that 

 obtaining in the existing Caudata. Some of the genera noticed 

 among the Archegosauridce, in which the skull is unknown, may 

 belong to this family. 



Family Dendrerpetid^e. — This family, which may be taken to 

 include the Brachiopina of Professor Miall, contains several genera, 

 of which the precise serial position and full affinities are at present 

 somewhat uncertain. The skull is parabolic, and marked by deep 

 pits ; the parasphenoid in the type genus has a short stem ; and the 

 teeth have irregular foldings at the base. The vertebrae were fully 

 ossified, and may have been of the embolomerous type. The type 

 genus Dendrerpeton is a medium-sized form occurring in the Car- 

 boniferous of Nova Scotia and the Permian of Bohemia, and char- 

 acterised by the orbits being placed near the centre of the skull. 

 Another group of genera, constituting the above-mentioned Brachio- 

 pina, appears to agree so closely with the type in cranial characters, 

 that it may at least provisionally be included in the same family. 

 The orbits are generally placed somewhat anteriorly. This group 

 comprises Brachyops, known by a single skull from the Mangli stage 

 of the Upper Gondwana system of India ; Micropholis (Petrophryne), 

 1 Diplovertebridce, see note, p. 1027. 



