238 PALEONTOLOGY 



relatively Larger capacity of the temporal fossae, and smaller 

 size of the orbits. These cavities in D. lacerticeps occupy the 

 middle third of the skull, but in D. tigriceps are wholly in the 

 anterior half of the skull. The profile of the skull in D. lacer- 

 ticeps begins to slope or curve down from a line parallel with 

 the back part of the orbits, but in D. tigriceps it does not begin 

 to bend down until in advance of the orbits. 



Genus Ptychognathus, Ow. — Three other species, showing 

 a remarkable angular contour of the skull, with strongly ridged 

 maxillary and upwardly produced mandibular bones, have 

 been subgenerically separated under the name Ptychognathus. 

 Their remains characterize the same formations as those of 

 Dicynodon. No evidence of the Dicynodont family lias yet 

 been met with out of South Africa. 



Fam. — Cryptodontia. 

 Upper as well as lower jaws edentulous, or with inconspicuous 

 teeth. 



Genus Otjdenodon, Bain. 



Sp. Oudcnodon Bainii. — The fossils on which the above 

 genus and species are founded are from a bluish argillo-ferru- 

 ginous limestone in South Africa, and form part of a collection 

 transmitted to the British Museum by A. G. Bain, Esq. 



One portion of the fossil skull includes all that part in 

 advance of the temporal fossre ; the fore part of the temporal 

 ridges, at the upper and back part of this fragment, curve as 

 they diverge from each other to tin 1 back part of tin 1 orbit. 

 The upper interorbital part of the cranium is nearly l!;it, with 

 the orbital margins slightly raised, and terminating anteriorly 

 in a low antorbital prominence; the least breadth of the inter- 

 orbital space is one inch. A slighl depression divides the 

 antorbital from the supranasal tuberosities. The nasal bones 

 form an almost flat rhomboid surface, from the contracted fore 

 pari of which the broad premaxillary part of the upper jaw 



