CIRCULATION OF BATRACFIIAN*. 



Fig-. 20. 



i. i. o t 



ap crc 



CIRCULATION OF A TADPOLK. 



Explanation of Fig-,26. Principal blood vessels of the Tadpole of the Sala 

 niander: the artery which arises from the only ventricle of the heart; 

 it divides into six branches which go to the thiee pairs of branchiae, and 

 there ramify ; (they are called branchial arteiies, alt.;} br. the branchiae, in 

 whi< h we see the distribution of the branchial arteries, and the origin o! the 

 branchial veins, (vb.) which receive the blood after it has passed through 

 the larnellfB of the branchiae ; those of the two lust pairs of branchiae unite 

 on each side to form a vessel, (c.) which, by uniting with its fellow on the 

 opposite side, forms the ventral aorta or dorsil vessel, (or.) which is directed 

 backwards, and distributes the blood to most of the body ; the branchial vein 

 of the first pa r of branchiae is bent forwards, and carries the blood towards 

 the head, (<,f.); 1. an extremely small anastomosing branch, which unites, 

 the branchial artery and vein, at the base of the first branchiae, and which, 

 by afterwards becoming larger, permits the blood to pass from the first of 

 these vessels into the second, without passing through the branchiae ; 2. a 

 email anastomosing branch which, in the same manner, establishes a com- 

 munication, between the artery and vein of the second pair of branchiae ; 

 3, a vessel, which, by a filament situate further in, also joins together the 

 artery and vein of the posterior branchiae ; o. the orbital artery ;ap. the 

 rudimental pulmonary arteries. 



Fig. 27. 1., t 



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CIRCULATION OF A TADPOLE, IN THE PROGRESS OF METAMORPHOSIS. 



"Explanation of Fip. 27. The same parts in a Tadpole in which the 

 bianchiae begin to lose their importance in respiration, and in which a part 

 of the blood goes from the heart to different partb of the body without pass- 



