48 ^ ALLEN 



ing obliquely along the ventral surface of the right geniohyoideus 

 muscle and above the right hyohyoideus inferior muscle. When 

 the median line between the 2 geniohyoideus muscles is reached 

 this vessel bifurcates, one branch running along the ventral sur- 

 face of each geniohyoideus muscle. Both of these forks supply 

 also the intermandibularis muscle. The short geniohyoideus 

 artery, vi'hich is the left one in this specimen, supplies only the 

 posterior part of the left geniohyoideus muscle. The largest of 

 the branches of the hyoidean artery is the hyoid arch artery 

 proper, which has been designated as the hranchiostegal artery 

 (Pis. I and II, figs, i and 12 ; Br.O.A.). This vessel is given 

 off a little cephalad of the interhyal and runs along the outer 

 ventral edge of the epi- and cerato-hyals. In the region of 

 each hranchiostegal ray an artery is given off ventrad to supply 

 the hyohyoideus superior muscles. In Scor^cBnichthys one 

 hranchiostegal artery does not supply all of the superior hyoi- 

 deus muscles. Three or 4 such vessels pass over the outer 

 surface of the epi- and cerato-hyals and supply from i to 3 

 hyohyoideus superior muscles ; the last one evidently corre- 

 sponds to the single hranchiostegal artery of Ophiodon. 



What might be called the thyroid artery (PL II, fig. 12 ; 

 Thyr.A.) arises either from the second right or the second left 

 efferent branchial arter3^ In Fig. 12 it arises from the second 

 right efferent artery, flows cephalad under the ventral aorta 

 and anastomoses with the first efferent branchial artery. Along 

 its short course 2 or 3 small branches could be traced to the 

 thyroid gland, one of them supplying also the second left 

 obliquus ventralis muscle. 



Pharynx Artery (PI. II, fig. 12; Phar.A.). — This vessel 

 may have its source from the third left or the third right efferent 

 branchial artery. In the specimen from which fig. 12 was 

 drawn it arose, caudad, from the third right efferent branchial 

 vessel and, passing obliquely over the ventral aorta it bifurcates 

 in the region of the combined afferent trunk of the third and 

 fourth branchial arches. The smaller rigJit pharynx artery 

 (PI. I, fig. 12; R. Phar.A.) supplies the right side of the 

 pharynx, the transversus ventralis muscle, and the right phar- 

 yngo-clavicularis externus and internus muscles : while the 



