442 Dr. C. W. Andrews — Extinct Egyptian Vertebrates. 



In this region the skull resembles that of Thalassochelys very nearly. 

 There are some differences, however, the most notable of which 

 being the greater length of the quadrate in the fossil. Nevertheless, 

 I prefer at present to refer this species provisionally to Thalassochelys, 

 with the specific name T. libyca. 



Stereogenys Cromeri, gen. et sp. nov. 



The most interesting of the Chelonian remains are several more 

 or less complete skulls of a Pleurodiran tortoise, which presents 

 a number of peculiar features. The Pleurodiran nature of this 

 species is shown by (1) the completeness of the quadrate ring for 

 the tympanum ; (2) the form of the articular surface of the quadrate. 



The temporal fossa is roofed as in Podocnemis alone among living 

 Pleurodira. In the Mesozoic Bhinochelys also the temporal fossa is 

 roofed in, but in quite a different manner from that occurring in 

 Podocnemis and our fossil. So far as I can determine, this species 

 approaches Podocnemis more nearly than any other Chelonian, but on 

 the other hand there are some very important differences. The most 

 important of these are found in the structure of the palate (Fig. 4a), 



A 



Fig. 4. — Skull and mandible of Stereogenys Cromeri. One-half natural size, 

 (A) Palatal surface of skull ; (B) upper surface of mandible. The pre- 

 maxillse are restored from another specimen, b.o. basi-occipital ; mx. maxilla ;. 

 na. internal nares ; p.mx. premaxillae ; pal. palatines ; pt. pterygoids ; 

 q. quadrate ; s.occ. supra -occipital ; sq. squamosal. 



in which the palatine bones {-pal.) are much longer than in 

 Podocnemis, and are produced inward towards the middle line, 

 where in some specimens they seem to have united in a median 

 suture, in others to have remained separated by a narrow cleft, 

 which in life was no doubt closed by membrane, so that in either 

 case the opening of the internal nares (?m.) was carried far back 

 to the level of the ectopterygoid wings. This arrangement of the 

 palatines seems to be unique among Chelonia. There is a small 

 anterior vacuity between the hinder ends of the palatal portions of 

 the premaxillse {p.mx.) and the maxillge {mx.). The pterygoids {'pt.) 



