ON THK STATUS OK lllKl.dNlA DKPKKSSA I'KY. 



18H 



The |)tery<i^()icl.s ill ( '. mi/dnf; (fig. 49e) aie inodio-latei-ally 

 eniargiiiated by a large huIcuh for tlie passage of tlie pterjgo- 

 niaiidibularis mnscle. This is entirely absent in the skull of 

 ('. (h'jiressii (figs. 47b and 49f) giving a flatter and broader 

 appearance to the roof of the pharynx. J twill be very intei'esiing 

 to note the correlated modification of tlie ptei-ygo-niandibularis 

 muscle to suit this condition, which, judging from (ladow's-*'^ 

 and Hay's-''* figures, prevails in Curettn caretta also (fig. 49b). 

 In this species however, the pharyngeal roof is not so broad. 



Fig. 49.— Pterygoid bones showing the variation of the pterygo- 

 mandibular siileus in the various marine turtles. 

 a. Colpochelys kempii. Garni. \b. Caretta caretta, Linn. 

 c. Carrtta re/iiivas'a, Ha.y. d. Eretmochelys imbricata, Linn. 

 ''. C/ieto>iia r/tytias, L.inn. /. C/ietom'a de/iressa, Qarm. 



The basisphenoid of ('. dejn-essa (fig. 47b) extends much 

 further anteriorly and separates the pterygoids along their 

 median suture for a correspondingly greater extent. Although 

 tliis varies a little with age in the Green Turtle it is never so 

 pronounced in that species as in C de2:iressa. In this character 

 it is approached by ErefmdcheJys imhricata'^ and Colpochelys 

 kei))jjii in both of which the basisphenoid is anteriorly more 

 pointed than in CJieloin'a i)iijd((ft. In the Green Turtle the 

 basisfihenoidal ridge is almost transverse and but slightly 



:<» Gadow— Cambr. Nat. Hist., Kept.. 1901, p. 379, fig. 84. 

 Si* Hay— Proc. U.S. Nat. Mus., xxxiv., 1908, pi. viii., fig. 1. 

 ^« Boulenger— Brit. Mus. Cat. Chelonia, 1889, p. 181, fig. 45. 



