114 EDWARD PHELPS ALLIS jr., 



satisfactorily determine where one ended and the other began. In the 

 specimen cut in horizontal sections, and which was doubtless slightly 

 older than the other, the two cartilages were distinct and separate, 

 and the artery was seen to pass outward in a narrow space between 

 the hind edge of the pterygo-quadrate and the anterior edge of the 

 hyomandibular. It then turned downward external to the anterior 

 edge of the hyomandibular and immediately posterior to the pterygo- 

 quadrate, which latter cartilage here slightly overlapped externally the 

 former, the artery thus lying in an angle between the adjoining edges 

 of the two cartilages. 



While in this position, and at a level ventral to the point where 

 the ramus hyoideus facialis leaves the truncus hyoideo-mandibularis 

 facialis, the artery sends a branch backward, internal to the ramus 

 mandibularis externus facialis, but external to the ramus mandi- 

 bularis internus facialis. Running backward along the external 

 surface of the hyomandibular this branch reaches the hind edge of 

 that element, slightly dorsal to the epihyal. There it gives off two 

 branches one of which turns upward and the other downward along 

 the hind edge of the hyomandibular, the latter branch passing over 

 to the postero-lateral surface of the epihyal, and then to the internal 

 surface of the postero-ventral edge of the ceratohyal, where it was 

 traced downward a certain distance in the hyoid arch. The remainder 

 of the main branch continues backward along the inner surface of the 

 gill cover, and soon breaks up into several branches, certain of which 

 seemed to connect with the afferent artery of the gill cover, to be later 

 described, though this connection could not be definitely established. 

 After giving off this posterior, opercular branch, the main artery 

 continues downward and forward in the angle between the hind edge 

 of the pterygo-quadrate cartilage and the lateral surface of the hyo- 

 mandibular, lying between the two mandibular branches of the facialis. 

 Before reaching the horizontal level of the dorsal edge of the cerato- 

 hyal, the artery turns sharply backward, along the outer surface of 

 the hyomandibular cartilage, and reaches the antero-mesial surface of 

 the epihyal, which element at this age is relatively much larger than 

 in the adult. The artery must here cross that part of the hyo- 

 mandibular cartilage where, in the adult, is found the interspace of 

 cartilage between the osseous hyomandibular and symplectic. From 

 the point where the artery turns sharply backward a branch is sent 

 downward and forward, as a direct continuation of the artery above 

 that point, and was traced, external to the hind end of Meckel's 

 cartilage, into the mandible. 



