74 



ALLEN 



face of the clavicles (see Fig. 3), and into these sinuses the ven- 

 tral prolongations of the pectoral sinuses terminate. The ante- 

 rior dorsal corner of the posterior ventral pericardial sinus is con- 

 tinuous with the anterior portion of the ventral pericardial sinus. 



Mut.m 



JVntVar 



.I.j.r. 



Fig. 8. Deeper dissection of the same specimen as Fig. 7 to show the origin 

 of the inferior jugular from the nutrient branchial veins and its course above 

 the ventral aorta. 



This sinus (Figs. 3, 4, 6, 7, 9 and 10, V.Per.S. {l) ) passes cepha- 

 lad along the lower side of the ventral aorta, and when midway 

 between the combined trunks of the third and fourth afferent 

 branchial vessels and the second pair of afferent branchial 

 vessels, it divides ; each fork, designated as the ^pharynx lym- 

 phatic vessel (Figs. 3, 6, 7 and 8, Ph.L.V.), passes at first 

 obliquely across the thyroid gland and the second afferent 

 branchial trunk. Here it bifurcates, the anterior fork going 

 along the side of the thyroid to the base of the first branchial 

 arch ; while the other stem continues along between the afferent 

 and efferent branchial vessels of the second arch and shortly 

 sends off a branch which traverses along behind the afferent 

 branchial trunk. Neither of these branches could be traced 

 farther than to the origin of the first branchial filaments. They 

 evidently only receive lymph from the connective tissue lining 

 the base of the second branchial arch and the thyroid gland. 

 Since no similar branch was found on any of the other branchial 

 arches this fork has been designated as a pharynx rather than 

 a branchial vessel. In well-injected specimens as is shown by 

 (Fig. 6, Thyr.L. V., and Fig. 3) there was found an additional 



