270 



CLAiss AMrmniA. 



Jmx 



Jtnx 



« 6 



Fig. 146.— Skull of Rana escuhnta (from Claus). a dorsal, 6 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) ; F vomer. 



present on many of the 

 trunk vertebrae of the 

 Urodeles. In tlie 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 the 

 coracoids (Fig. 147, 6). In 

 Anura the sternum lies 

 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, 



FIG. 147.-A. ventral, B, later^al view of the ^hich expands behind into 



shoulder girdle and sternum of rw^w cm?fl<u« fl,^ nartilno-inniKj -s-i-nhissfpr- 



(from Reynolds, after Parker). 1 scapula; ^^^^ CartUagmOUS XipniSter- 



2 suprascapula ; 3 coracoid ; 4 glenoid cavity ; nnm t 7 '^\ 



6 precoracoid 6 sternum. iiuiii \-^'^/' 



