DISTRIBUTION OF SUBCUTANEOUS VESSELS IN GANOIDS III 



aorta, and the first afferent branchial artery and the second 

 obliquus ventralis muscle ; so far as could be ascertained it 

 was the first vessel to join the inferior jugular. The latter 

 connection (Figs. 5, 6 and 7, J3r.L.T.(2}V.O.) passes up 

 between the second obliquus ventralis muscle, ventral aorta, 

 and second afferent branchial artery. In the specimen from 

 which Figs. 5 and 6 were drawn there was a large dorsal open- 

 ing in the inferior jugular (Fig. 6, Af.O.), which in front lead 

 into a sinus designated as (M) that received two sacs from the 

 rear (^). Into the left sac the corresponding fourth branchial 

 lymphatic trunk empties, and the right sac receives a short 

 trunk (Figs. 5 and 6, S. T.) that encircles the inferior jugular, 

 and communicates below with a ventral sinus (S). En route it 

 collects the fourth right branchial trunk (Fig. 5, Br.L,.T.($) 

 from the rear ; while the remaining third left branchial trunk 

 (Figs. 5 and 6, J3r.L.T.($)) empties directly into the inferior 

 jugular, a little in advance of sinus (S). 



In the specimen from which Fig. 7 was drawn the third and 

 fourth branchial lymphatic trunks had an entirely different 

 mode of ending from that described above. No dorsal sinus 

 emptied into the inferior jugular, but a ventral sinus (Fig. 7, S) 

 was present and occupied a similar position as in Fig. 5. Its 

 communicating trunk (S. T.) connected directly above with the 

 inferior jugular instead of encircling the right side of the in- 

 ferior jugular as in Fig. 5. The ventral sinus in Fig. 7, S, 

 received the third right branchial trunk in front, and in addition 

 the fourth left branchial trunk from the rear ; while the fourth 

 right and the third left branchial trunks terminated directly in 

 the inferior jugular. 



The course of the inferior jugular in the branchial region is 

 too irregular and complex to permit of a description. Fig. 6 

 gives a general idea of its form and its anterior communications. 

 Here it is simply a very thin irregular sinus, conforming to the 

 general arrangement of the branchial arches and the ventral 

 aorta and its branches. In the neighborhood of the union of 

 the third and fourth pair of afferent branchial arteries (Fig. 6, 

 A.Br.A.($) and (4)) it not only surrounds them, but passes 

 dorsad between them. 



Proc. Wash. Acad. Sci., July, 1907. 



