270 



CLASS AMPHIBIA. 



Jms: 



Jmx 



jfe 



Et 



Flo/146. Skull of Rana esculenta (from Claus). a dorsal, b ventral view. The membrane 

 bones of one side are removed. The cartilage is shaded dark. Et girdle-bone (spheneth- 

 moid) ; Fp frontoparietal ; J quadrato-jugal ; Jmx premaxilla ; MX maxilla ;. N nasal ; 

 Ocl exoccipital ; Pe prootic ; PI palatine ; Ps parasphenoid (right half cut away) ; Pt 

 pterygoid ; Ty squamosal (paraquadrate) ; V vomer. 



present on many of the 

 trunk vertebrae of the 

 Urodeles. In the Anura 

 they are generally absent, 

 but in a few forms (e.g. 

 Discoglossus , Xenopus) they 

 are present on the anterior 

 vertebrae. In no Amphi- 

 bian do the ribs reach the 

 , sternum. 



The sternum in the Uro- 

 deles is a cartilaginous 

 plate lying behind and 

 interposed between 

 coracoids (Fig. 147, #). 

 Anura the sternum 

 partly in front of and partly 

 behind the ventral union of 

 the coracoids (Fig. 148). 

 The part in front is called 

 the omosternum (episternum, 

 presternum), the part be- 

 hind is the sternum proper, 



Pro. 147.-A, ventral, B, lateral view of the which expands behind into 

 shoulder girdle and sternum of Triton cristatus +1^ porfilacrinniKs 

 (from Reynolds, after Parker). 1 scapula; 

 2 suprascapula ; 3 coracoid ; 4 glenoid cavity ; rmm 

 S precoracoid 6 sternum. * 



the 

 In 



lies 



