THE HEART AND ARTERIES OF POLYODON 



441 



J 



Fig. 17 Arterial su23ply of the rostrum. The cartilage is cross hatched. 



foramen in the cartilage. The two nutrient arteries, one from 

 either side, run obhquely forward and inward giving off anterior 

 and posterior branches. The latter is deep and reaches the 

 dorsal wall of the cartilage where possibly it sends through per- 

 forating branches. There are other perforating branches further 

 forward. The main stems of these nutrient arteries finally 

 fuse and the resulting median vessel is continued anteriorly 

 through the mucous tissue. It ends finally in one or more 

 perforating vessels. 



