On some Reptilian Remains from South Africa. 379 



the Indian Gavial). This genus and species is founded on the 

 rostral end of the upper and lower jaws of a Crocodilian Reptile, 

 with a single terminal nostril, situated and shaped as in Teleosaurus, 

 and indicating similarly long and slender jaws. Only the incisive 

 and canine parts of the dentition are preserved ; but these closely 

 correspond with the same parts in Galesaurus, the incisors being 

 equal and close-set, of simple conical form, and the canines suddenly 

 contrasted by their large size. In shape they resemble closely the 

 completely formed canines in Carnivorous Mammals. There is no 

 trace of successional teeth Original transmitted to the British 

 Museum by Governor Sir George Grey, K.C.B., from Rhenoster- 

 berg, South Africa. 



Fam. DicYNODONTiA. Subgenus Ptychogiiathus, Ow. (jrTv^ba, 

 ridge, yraQoi, jaw). —This subgenus is founded on four more or 

 less entire skulls, two retaining the lower jaw, referable to two 

 species. 



Ptychognathus declivis, Ow. — Plane of occiput meeting the upper 

 (fronto-parietal) plane at an acute angle, rising from below upward 

 and backward, as in the feline mammals ; fronto-parietal plane 

 bounded by an anterior ridge, extending from one superorbital 

 process to the other ; from this ridge the facial part of the skull 

 slopes downward in a straight line, slightly diverging from the 

 parallel of the occipital plane ; superoccipital ridge much pro- 

 duced and notched in the middle ; the occipital plane, owing to 

 the outward expansion of the mastoid plates, is the broadest 

 part of the skull, which quickly contracts forward to the ridged 

 beginnings of the alveoli of the canine tusks ; orbits oblong, 

 reniform, suggestive of the reptile having the power of turning the 

 eyeball, so as to look upward and backward as well as outward. 

 Remains of sclerotic plates. Nostrils divided by a broad, flat, upward 

 production of premaxillary, situated nearer the orbit than the 

 muzzle, smaller than in type Dicynodon ; temporal fossae broader 

 than long, and with the outer border longest; palate with single 

 large oval vacuity, bounded by palato-pterygoid ridges ; occipital 

 bypapophyses proportionally thicker than in Dicynodon tigriceps ; 

 no trace of median suture in parietal, which is perforated by a ' fora- 

 men parietale ;' frontals divided by a median suture and supporting a 

 transverse pair of small tuberosities ; anterior boundary-ridge of 

 vertex formed by the nasals and prefrontals, the outer surface of 

 both being divided into a horizontal and sloping facet ; lacryraal 

 bone extending from fore-part of orbit half an inch upon the face to 

 the nostril ; premaxillary long and single, its median facial tract 

 flat, with a low median longitudinal ridge ; maxillaries forming the 

 lower boundary of the nostrils, and uniting above with the pre- 

 frontal, lacrymal, and nasal bones, their outer surface divided by the 

 strong ridge suggesting the subgeneric name ; teeth of the upper 

 jaw restricted to the two canine tusks, the sockets of which descend 

 much below tlie edentulous alveolar border ; lower jaw edentulous, 

 dee[), and broad, with the f()re-j)art of the .symphysis produced and 

 bent up to meet the seemingly truncate end of the premaxillary, — a 

 2 C 2 



