oe 



Fig. 3966. Swimming-bladder (S, anterior, S', posterior, division) of the bleak; 

 ce. oesophagus; I, air-passage of the air-bladder leading into the oesophagus 



Fig. 396c. Circulation of the blood in a bony fish, au, auricle ; ven, ventricle ; 

 bar, bulbils arteriosus; ao, aorta; 6a, one of the four branchial arteries which 

 carry the blood to the gil|s, and afterwards unite to form the descending aorta 

 (doo); pc, portal circulation; vc, great descending vein (vena cava); kid, kidney. 



Fig. 396d. The structure of the minnow and the living fish. B n. nose; A~n, 

 nose-pit; gc, gill-cover: af, pectoral or arm -fin ; If, leg-fins or ventrals; df, dorsal 

 fin: s/, anal tin: c/, caudal fin: ms. mucous scales of the lateral line: e. optic 

 nerve; ea. ear-nerve leading from the brain; fir, gills; h, heart; t, oesophagus: s. 

 stomach; fc. kidney: v. vent; do, dorsal artery; a, air-bladder; 6, back-bone; 

 nw, nerve-cord or spinal cord. 



[To face page 435.] 



