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 



A GM AB AU EFj Efe CP EFJ 



AS 



AL 



VD Af.+ RB 



FlG. 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.) 



A, dorsal aorta. A B, basilar artery. A F.\, A F.2, A FA, afferent branchial 

 vessels of first, second, and fourth branchial arches. A L, lingual artery. A P, 

 pulmonary artery. A R, anterior cerebral artery. A S, posterior palatine artery. 

 A 7 1 , anterior palatine artery. A U, cutaneous artery. A V, pharyngeal artery. 

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

 sural vessel. F.I, E F.2. E F.3, E FA, efferent branchial vessels of first, second, 

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

 left auricle. R T, truncus arteriosus. R V, ventricle. V D, Cuvierian vein. 

 V H, hepatic vein. VI, posterior vena cava. V P, pulmonary vein. 



mesoblast, the somatopleure and the splanch- 

 nopleure, remain comparatively thin and are 



