MANDIBULAR ARTERY — AORTIC ARCH 111 



anterior, to the pocket. A branch of the artery is sent poste- 

 riorly, on either side of the pocket, to the adductor muscle. 



After giving off this branch to the angle of the gape, the arteria 

 mandibularis becomes much reduced in caliber and soon joins, 

 or is joined by, the afferent mandibular artery. The single artery 

 so formed, continuing onward, passes internal to the 'joint 

 ligament' of Goodey's descriptions, which extends from the 

 articulating ends of the mandibula and palatoquadrate to the 

 corresponding ends of the hyomandibula and ceratohyal, and is 

 then joined by the hyo-mandibular cross-commissural vessel. 

 The artery formed by the union of these three vessels represents 

 that portion of the primitive mandibular aortic arch of embryos 

 which lies dorsal to the hyo-mandibular cross-commissural 

 vessel and which is called by Dohrn the arteria spiracularis. 

 It and the hyo-mandibular cross-commissural vessel together 

 form the so-called definitive afferent pseudobranchial artery of 

 the adult; and, continuing onward, it supplies the spiracular 

 gill. At or near the point where the three vessels unite to form 

 the arteria spiracularis a variable number of branches are given 

 off. One of these branches runs dorso-anteriorly a certain dis- 

 tance along the lateral surface of the dorso-posterior edge of the 

 palatoquadrate. Another branch runs forward along the exter- 

 nal surface of the musculus adductor mandibulae and falls into 

 the mandibular branch of the arteria carotis externa. This 

 mandibular branch of the carotis externa is thus connected with 

 the afferent mandibular artery by two vessels, each of which is 

 apparently an anterior prolongation of a commissural vessel 

 connecting the latter artery with the posterior efferent artery of 

 the hyal arch. 



In my earlier ('11 b) descriptions and figures of the arteries in 

 this fish, the thyreoid, submental, mandibular and afferent 

 mandibular arteries as now described and identified are all 

 shown, as is also that branch of the mandibular artery (there 

 called the afferent mandibular artery) which is sent to the angle 

 of the gape, there to separate into maxillary and mandibular 

 portions. But the anterior prolongation of the lateral hypo- 

 branchial artery beyond the afferent mandibular artery as at 



