212 BULLETIN OP THE UNIVERSITY OF WISCONSIN. 



teries, E. B.-L, E. B.-IL. PL 9, and fig. 1, PL 10, leave 

 the gill, each gives off a branch which crosses the proximal edge 

 of the gill. The branch arising from the first efferent artery 

 forms the External Carotid, E. C, PL 9, and fig. 1, PL 10, 

 while the branch arising from the second efferent artery goes to 

 the second afferent branchial artery, E. B. a., PL 9, and fig. 1, 

 PL 10. The Second and Third Efferent Branchial Ak- 

 teries unite at the posterior edge of the second branchial carti- 

 lage. The vessel thus formed, C. V., PL 9, and fig. 1, PL 10,. 

 and the first efferent branchial artery are united by a short ves- 

 sel, A. B., PL 9, and fig. 1, PL 10, as soon as they enter the 

 buccal cavity, along the dorsal side of which they run. The 

 first efferent branchial artery, after giving off the above connect- 

 ing branch, A. B., makes a bend and runs directly cephalad as 

 the Internal Carotid, I. C, PL 9, and fig. 1, PL 10. The 

 vessel formed by the union of the second and third efferent ar- 

 teries, after giving off the pulmonary artery, P., PL 9, and fig. 1, 

 PL 10, is continued as one of the Aortic Roots, R. A., PL 9, 

 and fig. 1, PL 10. 



The Internal Carotid, I. C, PL 9, arises from the first ef- 

 ferent branchial artery at the point where the anastomosing 

 branch is given off to the conjoined second and third efferent ar- 

 teries. It runs along the medio-ventral edge of the masseter 

 muscle and the ventral surface of the parasphenoid bone making 

 two convex and one concave turn towards the outside. It pierces 

 the parasphenoid opposite the first branchial cartilage, continues 

 along its dorsal surface for a short distance, about 8 mm, pierces 

 it a second time, and, running along its ventral surface, ends in 

 the premaxilla. 



At a point just anterior to the first gill the internal carotid 

 gives off several branches. They pierce the parasphenoid bone 

 and emerge anterior to the pterygoid. The most posterior of 

 these branches, the Internal Inferior Maxillary, I. I. M., 

 PL 9, runs under the tympanicum to the ramus of the lower 

 jaw, where it gives off a branch to the digastric and mylohyoid 

 muscles, a branch to the branchial cartilages, and then continues 

 along the internal side of the ramus of the lower jaw, giving off a 



