TC 



TR 



FlG. 24. A I2-MM. TADPOLE DISSECTED FROM THE VENTRAL 

 SURFACE TO SHOW THE HEART, THE INTERNAL GILLS, THE BRAN- 

 CHIAL VESSELS, AND THE HEAD-KIDNEYS AND THEIR DUCTS. THE 

 TAIL, WHICH IS ABOUT DOUBLE THE LENGTH OF THE HEAD AND 



BODY, HAS BEEN REMOVED. X 22. (After Marshall.) 



A, dorsal aorta. A F.\, A F.3, afferent branchial vessels of first and th'rl 

 branchial arches. A L, lingual artery. CG, carotid gland. EA, junction be. 

 tween afferent and efferent branchial vessels of first branchial arch. E F.\, E F3, 

 efferent branchial vessels of first and third branchial arches. GM, glomerulus. 

 KA, archinephric or segmental duct. KM, Wolffian tubules. K P, prone- 

 phros or head-kidney. K S.\^ A'6".3, first and third nephrostomes of head-kidney - 

 L /, upper lip. LJ, lower lip. L P, hind limb. O A , aperture of opercular 

 cavity. O P, opercular cavity. R S, sinus venosus. R 7", truncus arteriosus. 

 R V, ventricle. TC, cloaca. TO, oesophagus, cut short. T R, rectal spout. 



66 



