140 



DEVELOPMENT OF THE FROG. 



Fig. 33. A 12 mm. tadpole dissected from the ventral surface to show 

 the heart, the internal gills, the branchial 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. 



A, dorsal aorta : AF,l, AF,3, afferent branchial vessels of first and third 

 branchial arches : AL, lingual artery : CG, carotid gland : EA, junction 

 between afi"erent and efferent branchial vessels of first branchial arch : 

 EF,i, EF,3, eJBferent branchial vessels of first and third branchial arches : 

 GM, glomerulus : KA, archinephric or segmental duct : ^ KM, Wolffian 

 tubules: KP, pronephros or head kidney: KS,1, KS,3, first and third 

 nephrostomes of head kidney : LI, upper lip : LJ, lower lip : LP, hind 

 limb : OA, aperture of opercular cavity : OP, ov)ercular cavity : RS, sinus 

 venosus : RT, truncus arteriosus : RV, ventricle : TO, cloaca : 

 TO, oesophagus, cut short : TR, rectal spout. 



