i4o 



THE COMMON FROG. 



[chap. 



1 Sigs 



Fig. 85. 



Fig. 87. 



Fig. SS. 



Fig. 85.— Diagram representing the primitive aortic arches of Mammals and Sau- 

 ropsidans (after H. Rathke). n, common trunk, or root, of the aorta ; b, b, the 

 two branches into which it divides, and which give off the successive arches i, 2. 

 3, 4, and 5, which end in c, c, two vessels which again unite to form d, the de- 

 scending, or dorsal, aorta. 



Fig. 86. — Diagram representing the vessels and aortic arches of a Lizard, with the 

 changes induced on the primitive condition (after H. Rathke). «, a, internal 

 carotids ; b, b, external carotids ; c, c, common carotids ; d, d, anastomosis be- 

 tween the internal carotids and the secondary aortic arches ; e, e, right main 

 aortic arch ; /,/, the subclavian arteries (which give off the vertebral, here not 

 represented) ; g; commencement of the great dorsal aorta ; h, h, left main aortic 

 arch ; i, i, i, pulmonary arteries ; k, k, rudiments of the first (right and left) 

 aortic arches, — Nos. 5, 5, of P"ig. 85. 



Fig. 87. — Diagram representing the main arteries of a Bird (fowl) with the changes 

 induced on the primitive condition (after H. Rathke). a, a, internal carotids ; 

 b, b, external carotids ; c,c, common carotids ; d, root of main aortic arch (here 

 right) ; ^, arch of the same ;_/, right subclavian (which arises from the anastomosis 

 of the first two right primitive aortic arches) ; g; commencementof the descending 

 aorta ; //, h, left subclavian ; i, i, i, pulmonary arteries ; k, right, and /, left, 

 rudiments of the primitive aortic arches. 



Fig. 88.— Di.agram representing the main arteries of a Mammal with the changes 

 induced in the primitive condition (after H. Rathke). n, b, c, carotids, as before ; 

 d, root of main aortic arch (here left) ; e, arch of the same ; /, commencement 

 of descending aorta ; g; left vertebral artery ; h, left subclavian ; i, right sub- 

 clavian ; k. right vertebral artery; /, continuation of right subclavian; fH, pul- 

 monary artery; n, remnant of left primitive aortic arch. 



