XIII 



PHYLUM CHORDATA 



523 



as usual, developed from a special bony centre, and a distinct 

 suture is often recognisable between it and the scapula unti] a 



Icr- fr 



s.o e 



FIG. 1132. Skull of Dasyurus (lateral view). al.sph. alisphenoid ; ang. angular process of 

 mandible ; /r. frontal ; ju. jugal ; Icr. lacrymal ; max. maxilla ; nas. nasal ; oc..cond. occipital 

 condyle ; orb. sph. orbitosphenoid ; par. parietal ; par. oc. paroccipital process ; p. max. pre- 

 maxilla ; s. oc. supra-occipital ; sq. squamosal ; sq'. zygomatic process of squamosal. 



eac.oc 



bas.oc 



FIG. 1133. Skull of Rock Wallaby (Petrogale penicillata) (ventral view). Letters as in 

 Fig. 1132, except ali. alisphenoid. In addition, bas. oc. basi-occipital ; bas. sph. basi-sphenoid ; 

 ex.oc. ex-occipital ; pal. palatine ; pt. so-called pterygoid ; ty. tympanic. 



comparatively late stage. In the young condition (when the foetus 

 is attached to the teat), the coracoid is comparatively extensive and 



