The Development of the Frog 71 



easily seen in the transparent tail of the young 

 tadpole (Fig. i , M-O). The lateral plates of the 



h GM AB AU EF.3 EFz CP ERt CA 



J_\ 



4-LU\ 



.^R 



AT 



Tl. RB RA RV AK. RT 



Fig. 26. — A diagrammatic figure of the head and neck of 



A I2-MM. TADPOLE, FROM THE RIGHT SIDE, TO SHOW THE HEART AND 

 BRANCHIAL VESSELS. ThE GILLS AND THE GILL CAPILLARIES ARE 



NOT REPRESENTED. X 35- (After Marshall.) 



Ay dorsal aorta. A B, basilar artery. A Al, A F.2y A 7^.4, afferent branchial 

 vessels of first, second, and fourth branchial arches. A Z., lingual artery. A /*, 

 pulmonary artery. A J?, anterior cerebral artery. A S, posterior palatine artery. 

 A 7\ anterior palatine artery. A £/, cutaneous artery. A K, pharyngeal artery. 

 CA, anterior commissural vessel, CG, carotid gland. CP, posterior commis- 

 sural vessel. EF.\, EF.)i. E F.%, E FA, efferent branchial vessels of first, second, 

 third, and fourth branchial arches. G M, glomerulus. RA, right auricle. RBj 

 left auricle. R T, truncus arteriosus. R V, ventricle. " VD^ Cuvierian vein, 

 V H^ hepatic vein. VI, posterior vena cava. VP, pulmonary vein. 



mesoblast, the somatopleure and the splanch- 

 nopleure, remain comparatively thin and are 



