168 MR. D. M. S. WATSON ON 



suffers from the disadvantage that whilst emphasising resem- 

 blances it is liable to obliterate remembrance or recognition of 

 differences. 



As in my opinion the study of early Tetrapods is at present 

 suffering from an insufficient appreciation of the differences that 

 do exist, the following scheme will follow Prof. Osborn's method, 

 although I fully realise that this course leads to a multiplication 

 of Orders and to the placing of many types as incerta sedis. 



BATRACHIA. Macartney, 1802. 



Tetrapods which, either in a larval stage or persistently, 

 breathe by gills. 



Super-Order LABYRINTHODONTIA (Owen). 



Amphibia with a roofed skull, a lower jaw consisting of at 

 least eight bones on each side, and vertebrae consisting of neural 

 arches and intracentra in all forms, with pleurocentra in addition 

 in most. 



Grade EMBOLOMERI Cope. 



Labyrintliodonts with large well-ossified basioccipital and basi- 

 sphenoid. Occipital condyle single or triple. Pterygoids with 

 a large palatal part, articulating by movable facets with definite 

 basipterygoid processes of the basisphenoid. Interpterygoid 

 vacuities very small. Tabulars and dermo-supraoccipitals with- 

 out occipital extensions. 



Family ANTHRACOSAURiDiE Cope, 1875. 



Embolomeri with a single occipital condyle. No specialised 

 sacral vertebrse. Clavicles flat plates with parallel anterior and 

 posterior margins. A ventral armour of scutes. Primitively 

 aquatic. 



Anthracosaurus Hux. Lower Carboniferous, Scotland. 



Pteroplax Hancock & Atthey. L. ? Coal Measures, North- 

 umberland . 



PTioliderpaton Hux. M, Coal Measui-es, Yorkshire. 



? Erpetositchus * Moodie. U. Coal Measures, Kansas. 



Family Loxommid^, nov. 



Embolomeri with triple occipital condyles and enlarged orbits. 

 Post-ci'anial skeleton not known. ? No ventral armour. 



Loxomma Hux. L. Cai-boniferous, Scotland. 



" Loxomma cdhnani." Lower and Middle Coal Measures, 

 Lanarkshire, Fifeshire, Northumberland, Staffordshire. 



Baphetes Owen. Coal Measures, Nova Scotia. 



" Loxomma hohemicicm." L. Permian, Nyran, Bohemia. 



* Name preoccupied. E. T. Newton, 1893, 



