RANA. 



341 



Respiratory. 



rectum which opens into the cloaca. From its ventral wall, 

 close to the cloacal aperture, is a large bilobed urinary 

 bladder. 



Close to the pancreas, and near the head of the rectum, 

 is a round reddish spleen, one of the ductless glands. 



At the extreme front end of the abdominal cavity there 

 lies dorsally a pair of lungs. Each rests loosely in the cavity, 

 but is attached anteriorly to the oesophagus. 

 If the lungs be inflated by a blowpipe through 

 the glottis they will be seen to consist of hollow sacs of 

 great elasticity. When punctured they return to their former 

 small bulk and soft condition. 



Fig. 240.^rDiAGRAM OF Venous System of a Frog. 



(Ventral view.) ^ ^ 



External Jugular. 

 Lingual. j| Sinus Venosus. 

 Mandibular. | , yf \ Precaval. 

 Internal Jugular. \^%A^ ^ / 

 Subscapular. \^^*>|YX / V % Subclavian. 

 Innominate. -~II>iJLf.l/ / l\ \ / Brachial. 



Musculo- 

 cutaneous. 



Renal Portal, 



Sciatic, 

 Femoral 



The anterior abdominal is unlabelled, but is seen running forwards from the 

 two pelvics to the portal. 



The frog fills its buccal cavity with air through the nares, 

 and then pushes upwards the floor of the cavity with its 

 hyoid cartilage (or lingual plate). This forces the air down 

 to the lungs and effects inspiration. The air is expired by 

 the elastic walls of the lungs.'"' We may notice that the 



* The expiration may be assisted by contraction of the abdominal muscles upon 

 the viscera. 



