772 THE WHITE EIVEE FAUFA. 



The characters of the preniaxillary bone, fontanelle, dentition, coro- 

 noid, dentary, splenial bones, and meckelian groove, place this genus out 

 of the pale of the acrodont families. The parietals and vertebrae are dis- 

 tinct from anything known among the geccos. There is no resemblance in 

 essentials to the Amphishcenia, so that we must look for its place among 

 the numerous pleurodont families. Here the absence of the knowledge of 

 the periotic bones and sternum somewhat embarrasses us; but other indica- 

 tions are clear. The coincidence of the want of parietal fontanelle with the 

 lateral frontal plates refers us at once to the Leptoglossa or Diploglossa ; a 

 reference confirmed by the simple frontal, and strong cranial arches. The 

 massive form of the surangular bone, and reduction of the angular, at once 

 distinguishes Peltosaurus from any known family of the tribe Leptoglossa, 

 and constitutes a point of near resemblance to the GerrJionotidoe. This ap- 

 pears to be a real affinity, which is further confirmed by the presence of a 

 symmetrical dermal scutellation on the top of the head. 



Eeferring Peltosaurus, therefore, provisionally to the Gerrhonotidce, it 

 remains to consider the generic characters. The temporal fossa was not 

 roofed over by true bone, though the border of the postfrontal encroaches 

 on it ; and it is rather small. The orbits, on the other hand, are large, and 

 the malar bone forms a segment of a circle. The parietal thins out behind, 

 and its posterior border has a subround excavation. Thetwo median der- 

 mal scuta, which left their impressions on the parietal bone, represent the 

 interparietal and postinterparietal plates respectively ; the latter especially 

 characteristic of the Gerrhonotula', and not found in leptogloss or diplogloss 

 families generally ; those possessing it being the Lacertidce in the former, 

 and Anguidce in the latter. The most prominent character which distin- 

 guishes this genus from Gerrhonotus is the existence of the osseous scuta 

 which covered the body. Even the form of these is similar to the corre- 

 sponding dermal scuta of the existing genus. They are rectangular and are 

 arranged in transverse bands on the body, those of one row overlapping the 

 bases of those of the next row posteriorly, or imbricated. The scuta of 

 each row are joined on their long sides. By minute suture. 



