GENERAL STRUCTURE AND ORDERS. IO37 



skull ; and the apparently allied Gonioglyphis, from the Panchet 

 stage of the Lower Gondwanas of India. Pachygonia (fig. 952), of 

 the latter deposits, may also be provisionally included in this group. 

 From the Maleri stage of the Upper Gondwanas we have also a 

 Labyrinthodont apparently closely allied to Capitosaurus, and thus 

 indicating a precise parallelism in the evolution of the group in the 

 Indian and European horizons. Here also we may perhaps place 

 a small form described under the provisional name of Glypto- 

 gnatfais, from the Indian Panchets. Metopias, of the Continental 

 Keuper and Rhaetic, is distinguished from the preceding genera by 

 the more anterior position of the orbits ; Labyrinthodon, of the 

 English Keuper, being probably allied. The second group is repre- 

 sented by Diadetognathus, of the Warwickshire Trias, in which the 

 mandible has no inner articular buttress. 



Of Uncertain Family. — Here may be mentioned the genus 

 Eosaurus, founded upon large vertebral centra (fig. 970), from the 



Fig. 970. — Two vertebral centra of Eosaurus acadiamts ; from the Carboniferous 

 of Nova Scotia. (After Marsh.) 



Carboniferous of Nova Scotia, which were regarded by Professor 

 Marsh as belonging to an Ichthyosauroid Reptile, but which really 

 indicate a large Labyrinthodont, perhaps referable to the Masto- 

 donsanridcE. 



Leaving out some ill-defined genera, mention must be made of 

 Pteroplax, of the British Carboniferous, which was formerly classed 

 next to Batrachiderpeton. The skull is elongated, and remarkable 

 for the incomplete orbits ; while it appears that many of the ordi- 

 nary bones are wanting. The cranial bones have a pitted sculpture ; 

 and the vertebral centra are thick and fully ossified. 



