186 EXPLANATION OF THE PLATES. 



whilst the vertebrae and sternal plates, also figured and described 

 as belonging to PteropJax, are probably remains of Anthracosau- 

 ru8 Russelli. 



My acknowledgments arc due to my fiiends Dr. Embleton and 

 Mr. William Dinning ; to the former for his assistance in the 

 above description, and to the latter for the accurate and beautiful 

 drawings illustrative of that description. 



EXPLAI^ATION OF THE PLATES. 



PLATE XV. 



Upper surface of the smaller cranium of Pteroplax cornuta, of the natural 

 size ; the portions of ribs mentioned in the text as Ij'ing upon and 

 under the cranium are seen. /•>., frontal bone ; Pt.Fr., postfrontal ; 

 Pt. 0., postorbital; Pa., parietal; Sg., squamous; Ep., epiotic; Q., 

 quadrate; Ex. 0., exoccipital ; S. 0.. so-called supraoccipital. The 

 parietal foramen and the epiotic horns are sufficiently evident. 



PLATE XVL 



Fig. 1. Under surface of the larger cranium of Pteroplax cornuta, of the 

 natural size. />., frontal bone ; Pf. Fr., postfrontal ; Pt. 0.. post- 

 orbital ; Sq., squamous; Ep,, epiotic; (^., quadrate; Oc, occipital- 

 Fig. 2. A, B. Scutes : A upper, B under surface. 

 Fig. 3. A, B, C. Three digital bones. 



