136 



In Esox the artery has largely aborted and could not be traced the 

 full length of the ceratohyal. In Amia, it traverses the suspensorial 

 apparatus as an important vessel, and sends a large branch into the 

 mandible, but the connection with the pseudobranch, which exists in 

 embryos (Allis 1900), could not be found in the adult: and this 

 condition of these arteries in the adult Amia seems to definitely 

 establish that the mandibular artery of Allen's (1905) descriptions 

 of the Loricati is a branch of the afferent mandibular arteiy and 

 not, as Allen was led to conclude, a branch of the external carotid. 



A primary afferent hyoidean artery, arising from the truncus 

 arteriosus, is found in the adult Amia alone of all the fishes examined. 

 There is however, in the adults of all these fishes, Amia included, a 

 branch of the afferent mandibular artery that is given off just before 

 that artery perforates the hypohyal and that runs upward in the 

 hyoidean arch along the posterior surface of the ceratohyal ; that is, in 

 the position of an arterial vessel of the hyoidean and not of the man- 

 dibular arch. In Acipenser, both in larvae and in the adult, a strictly 

 similar vessel is found, and as, in that fish, it is said by Osteoumoff (1907) 

 to be developed from a ventral prolongation of the posterior efferent 

 artery of the hyoidean arch, it quite undoubtedly has that origin in 

 Amia also, and hence also in teleosts. I have accordingly called it the 

 secondary afferent hyoidean artery. In Amia, this artery is continuous 

 dorsally Avith the facialis branch of the hyo-opercularis artery, a com- 

 plete arterial arch thus being formed in the hyoidean arch of the 

 adult of this fish. Allen does not give this secondary afferent artery 

 in his descriptions of the Loricati, nor do I find it in either Scorpaena 

 or Trigla, but it would seem as if that branch of the so-called hyoidean 

 (afferent mandibular) artery of Allen's descriptions that goes to the 

 geniohyoideus muscle might be a remnant of the artery. 



The efferent mandibular artery of the adult Amia is formed, as 

 it is in larvae (Allis, 1900), by that portion of the so-called efferent 

 pseudobranchial artery, or arteria ophthalmica magna, that lies between 

 the pseudobranch and the short commissural vessel that connects the 

 efferent pseudobranchial artery with the internal carotid (lateral dorsal 

 aorta) as the latter artery traverses the orbital opening of the myodome 

 (Allis, 1897), together with one half of the short commissural vessel; 

 and that portion of ■ the so-called efferent pseudobranchial artery that 

 lies distal, or cephalad, to that commissure is, alone, the homologue 

 of the arteria ophthalmica magna of selachians. In the adult of each 



