128 



the direction of the blood current in it is not known, the artery is 

 doubtless, as Silvester (1904, p. 94) concludes, a second, but secon- 

 dary, afferent pseudobranchial artery. 



Anterior to this secondary afferent pseudobranchial artery, the 

 orbito-nasal artery has its origin from the lateral dorsal aorta. The 

 lateral dorsal aorta then turns inward onto the dorsal surface of the 

 parasphenoid, passing through a notch on the anterior edge of the 

 ascending process of that bone, and fuses, in the median line, with 

 its fellow of the opposite side, thus completing the circulus cepha- 

 licus. From the median point of the circulus a single artery arises 

 and running upward pierces the roof of the myodorae and enters the 

 cranial cavity, as already described. 



It is thus seen that in no one of the three teleosts here under 

 consideration does the afferent mandibular artery, the so-called arteria 

 hyoidea of current descriptions, perforate the hyomandibular, and it 

 is highly probable that this artery does not perforate that element in 

 any teleost. The hyomandibular is however perforated, in each of the 

 three fishes here under consideration, by an arterial vessel that ap- 

 pears as a branch of the external carotid and that is quite certainly 

 the homologue of the facialis branch of the hyo-opercularis artery of 

 my descriptions of Amia. Having found this facialis branch of the 

 external carotid in each of these three teleosts, I have looked for it 

 again in the Loricati also. In these latter fishes Allen (1905) does 

 not describe such a branch of the carotid, and in the several speci- 

 mens of these fishes that I examined in connection with an earlier 

 work (Allis, 1910), a work relating primarily' to the skull and nervous 

 system, the smaller branches of the carotids, and even the terminal 

 portions of the larger branches, did not enter into the investigation. 

 Furthermore, in the one specimen in which the vessels that traverse 

 the facialis canal through the hyomandibular were examined, a 45 mm. 

 Scorpaena, the only vessel there found that seemed to be an artery 

 was a branch of what I described as the vessel x. Other vessels 

 traversing the canal were found, but they were all either venous or 

 lymphatic in appearance, and were not traced. I have now, however, 

 had all the vessels that traverse • this canal traced, by my assistant, 

 Mr. John Henry, in a 40 mm. specimen of Scorpaena scrofa and in 

 a 37 mm. specimen of Clinocottus, and he finds on both sides of the 

 head of the latter and on one side of the head of the former an 

 arterial vessel that joins the external carotid after that artery has 



