182 



RECORDS OF THE AUSTRALIAN MUSEUM. 



Fig. 4S.—a. ChelonJa depressa, Garm. Lateral view of skull 



of specimen No. 7. Enlarged slightly, b. Chelouia niydas, 



Linn. Lateral view of skull of a specimen approximately 



the same size as that of C. drftre^sa. 



be individual variations. This condition is apparently very 

 uncommon, and vpas perhaps first recorded by Sir 

 Richard Owen-^*' — "In CheJ. iiiydas the malar approaches the 

 mastoid very closely and sometimes touches it by the jiosterior 

 angle, thus separating the squamosal from the postfrontal." 

 In recent osteological nomenclature the malar becomes the 

 jugal, the mastoid is our squamosal, while Owen's squamosal 

 is our quadratojiigal. In the Green Turtle the anterior ( jugulai-) 

 flange of the quadi-atojugal is bayetl ventrally to a lesser extent 

 than in C. depn'ssa, making the quadrate pedicle appear longer 

 in the latter species. 



' It is in the basicranial constituents that the most reliable 

 points of difFerence between the two species can be noticed. 

 In some of these characters Cheloiiia depressa shows unmistak- 

 able resemblance to Colpocheliis l-§vipii, which has been 

 beautiful l}-^ figured by Dr. Hay.37 



38 Owen— Hist. BritrFoss^ Kept., i., 1849-84. p. 33. 



•'" Hay — Foss. Turtles N. Amer., Carneijfie Inst., piibl. ITi. 1908, pi. i., 

 figs. 1-4, pi. ii., and Proc. U.S. Nat. Mus., xxxiv., 1908. pi. vi., pi. vii., 

 figs. 2-4, pi. viii., fig. 2, pi. ix., figs. 2 anil 4. 



