XIII 



PHYLUM CHORDATA 



523 



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

 suture is often recognisable between it and the scapula until a 



nas 



ICT- J^ J 



P?'''^ 



s.oc 



OC.COTh 



^d- 



pur.oc 



Fig. 1132. — Skull of Dasinirus (lateral view). cd.spli. alisphenoid ; ang. angular process of 

 mandible ; fr. frontal ; ju. jugal ; Icr. lacrymal ; max. maxilla ; nas. nasal ; oc. cond. oceipital 

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

 maxilla ; s. oc. suprA-oocipital ; sq. squamosal ; sc/, zygomatic process of squamosal. 



bas.oc 



Pig. 1133.— Skull of Rock Wallaby {PttrogaU penicillata) (ventral view). Letters as in 

 Fig. 1132, except ali. alisphenoid. In addition, 60s. oe. basi-occipital ; lias. sph. basi-sphenoid ; 

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



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

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



