312 



THE AMERICAN NATURALIST 



[Vol. XL 



The Arterial System 



From the anterior edge of the ventricle leads forward the thick- 

 walled conus arteriosus (Fig. \2,T.). It is of considerable length, 

 and is more or less bent towards the right. It becomes consid- 

 erably enlarged anteriorly to form the conspicuous bulbus arte- 

 riosus {B.). The bulbus arteriosus gives off from its anterior 

 end, on each side, four branchial vessels (Fig. 12, 1, 2, 3, 4), which 

 diverge slightly as they pass towards the side. All four of these 

 arches are united with one another, just beyond the gill cleft (G. C). 

 but it is from the second and third that the real systemic arch (S.), 

 is chiefly formed. This complicated arrangement of the branchial 

 blood vessels is, in the main, similar to that described in the Jap- 

 anese hellbender by Osawa, but differs considerably from the 

 description given by Chapman ('93), also of the Japanese sala- 

 mander. 



The first arch, which may be called the carotid, extends for 

 some distance as a single vessel and then becomes slightly swol- 

 len to form a sort of carotid gland (C. G.), similar to that found 

 in the frog. From the median side of the carotid gland is given 

 off an artery which is distributed to the hyoid apparatus and the 

 floor of the mouth, and may hence be called the lingual (L.). 



Just beyond the carotid gland the arch divides and reunites 

 again, giving off one or two small vessels to the neighboring parts. 

 Then, after continuing for some distance as a single vessel, it 

 divides into two vessels, the external and internal carotids (E. C, 

 /.). Just before dividing into the external and internal carotids 

 the arch is connected with the main systemic arch by a vessel that 

 is called by Marshall the ductus Botalli, by Osawa the ramus com- 



The second and third branchial arches ( Fig. 12, .i), after run- 

 ning more or less parallel to each otlKM- to a point l):i( k of the caro- 

 tid gland, unite to form the main sijslnnic <irrh iN.i. The third 

 arch runs along the anterior margin of the gill ck-ft ((i. C), and 

 gives off, just before uniting with the second arch, a branch to 

 the fourth branchial arch. This branch may be called the ductus 

 Botalli ip. B.). 



