340 



ZOOLOGY 



SECT. 



a suture. There is a broad palate formed by the plate-like vomers, 

 palatines, and pterygoids. 



In the Chelonia (Figs. 1002, 1003) all the bones, including the 

 quadrate, are solidly connected together. Transverse bones 

 (ectopterygoids), lacrymals, orbitosphenoids and alisphenoids are 

 absent. The place of alisphenoids is taken to a certain extent 

 by vertical downward plate-like extensions of the parietals, the 

 lower part of the plates perhaps representing the epipterygoids of 

 Lizards. There may be open temporal fossae, the inferior boundary 

 of which (inferior temporal arch) may be incomplete owing to the 

 absence of the quadrato-jugal (paraquadrate), or the entire temporal 

 region may be covered over (Turtles, Fig. 1003) by a sort of false roof 

 formed of expansions of the post-f rentals (ph), parietals (par), and 



squamosals (sq.) 

 with the jugal (/) 

 and quadrato-jugal 

 (q.j). The immov- 

 ably fixed quad- 

 rates (Fig. 1003, 

 qu, and Fig. 1002, q) 

 are modified to 

 afford a part or the 

 whole of the rim for 

 the support of the 

 tympanic mem- 

 brane. The occi- 

 pital condyle 



FIG. 1002. Lateral view of skull of Emys europaea. Coc. A ^ , 



occipital condyle ; F. frontal ; F*. post-frontal ; /.foramen Sometimes 

 by which the olfactory nerve enters the orbit ; lug. jugal ; 

 M. maxilla; Md. mandible; Mt. tympanic membrane; 

 Na. external nares ; OL exoccipital ; Osp. supra-occipital ; 

 P. parietal ; Pf. pre-frontal ; Pmx. pre-maxilla ; Qjg. 



-Co* 



s 



vnrnpr ti nn 

 ' r \ v ) 1S 



paired. The pala- 



, 7X 



quadrato-jugal ; Qu. quadrate ; Si. inter-orbital septum ; tines (pal) are ap- 

 Squ. squamosal ; Vo. vomer. (From Wiedersheim's Com- - nrrkV1 ' YY , Q f or I Q A 

 parative Anatomy.) prOXimatCQ ana 



give off palatine 



plates, which for a short distance cut off a nasal passage from the 

 cavity of the mouth. Nasals are usually absent as separate bones. 

 The premaxillse are very small. The rami of the mandibles are 

 stout, and are firmly united together at the symphysis. 



In the Crocodiles (Figs. 1004, 1005), as in the Chelonia, the 

 quadrate* (Qu) is firmly united with the other bones of the skull. 

 There is* a membranous and cartilaginous inter-orbital septum. 

 There are no distinct orbitosphenoids, but alisphenoids are well 

 developed. The orbit is separated from the lateral temporal 

 fossa by a stout bar situated somewhat below the surface, and 

 formed of processes from the post-frontal, jugal and ectopterygoid. 

 The lateral temporal fossa is bounded below, as in Sphenodon, 

 by an inferior temporal arch composed of jugal and quadrato- 

 jugal (paraquadrate). The f rentals are early united into one, 



