BLOOD-VASCULAR SYSTEM OF THE LQRICATI 47 



Hyoidcan Arteries (Pis. I and II, ligs. i and 12; Ilyo.A.). 

 — A short distance above the source of the inferior hyo hyoideus 

 arteries, 2 large hyoidean arteries are given off to the hyoid 

 arch and the adjacent region. After reaching the hyoid arch 

 from the inside, a little behind the hypohyals, the main trunk 

 runs along the dorsal surface of the cerato- and epi-hyals ; 

 making a dorsal bend in front of the interhj-al it crosses under 

 the preopercular, and after passing through a foramen, which 

 is formed by the symplectic, hyomandibular, preopercle, and 

 quadrate, anastomoses with the faclalis-mandibidaris artery 

 (PL I, fig. I ; F.Man. A.). In the embryo the hyoidean artery 

 probably furnished the entire blood for the pseudobranchia ; the 

 current of blood in the facial-mandibular artery was dorsad 

 toward the carotids. Also in the adult it would be possible for 

 the blood from the h3^oidean artery to flow dorsad in the facial- 

 mandibular artery as well as ventrad, however, since the facial- 

 mandibular is a much larger artery than the hyoidean, it is not 

 probable that much of the blood from the hyoidean artery runs 

 counter to the current of the facial-mandibular artery. It also 

 might be possible at times for the blood in the hyoidean artery 

 to flow ventrad, that is toward the efferent branchial artery. 

 From Miiller's (50), Stannius' (74), and Emery's (24) descrip- 

 tions, one would infer that the h3^oidean arter}^ in most bony 

 fishes supplied the pseudobranchia, but in Ophiodon the blood 

 supply for the pseudobranchia, which will be considered later, 

 comes from a branch of the external carotid artery. 



The first branch to be given off from the hyoidean artery is the 

 lingual artery (PI. II, fig. 12 ; Lin. A.). This vessel leaves the 

 hyoidean arter}^ close to the efferent branchial artery, shortly be- 

 fore the hyoidean arter}- reaches the hyoid arch, and each lingual 

 artery runs cephalad along the ventral surface of the glossohyal. 

 Immediately after the hyoidean artery reaches the hyoid arch it 

 gives off the geniohyoidcus artery (Pis. I and II, figs, i and 12 ; 

 Ghs.A.) to the geniohyoideus muscle. One of these arteries is 

 much longer than the other ; sometimes it is the right and again it 

 is the left. In the specimen from which fig. 12 was drawn, the 

 right artery was the longer ; it passed entirely around to the outer 

 ventral surface of the ceratohyal and then curved cephalad, pass- 



