(•) WILLIAM F. ALLEN 



could l)e ascertained they were destined to supply the blood vessels 

 of the haMnal canal. For their branches were observed going to 

 and breaking up on the surfaces of the caudal and intersegmental 

 arteries. In the dissection from which fig. 10 was drawn the main 

 stem of the minor caudal artery ran along the right side of the 

 caudal artery to the fifth vertebra from the last, when it crossed 

 to the opposite side and continued caudad on the left side of the 

 caudal artery to the end of the last vertebra, where it bent dorsad 

 with the caudal artery to the interval between the two hypural 

 bones. In the single specimen in which the origin of the minor 

 caudal artery was traced, it was found to branch off from the lef c 

 side of the dorsal aorta a few millimeters cephalad of the pos- 

 terior end of the kidney. The main stem passed caudad along 

 the left side of the aorta from which a short branch was given off 

 cephalad. Shortly after leaving the body cavity the minor cau- 

 dal artery bends to the ventral surface of the caudal artery where 

 it separates into two forks of about equal size, the main stem trav- 

 eling caudad on the right side of the caudal artery and the minor 

 stem on the left. Beside the capillary branching to the blood ves- 

 sels, as mentioned above, there are frequent cross branches be- 

 tween these two stems of the minor caudal artery, producing 

 a ladder-like appearance. In some dissections of Scorpsenichtys, 

 as in fig. 5, the minor caudal artery in traversing the hypural inter- 

 val was situated ventrad of the caudal artery, but in other dis- 

 sections of Scorpaenichthys and in the Clinocottus series, as shown 

 in figs. 7 and 8, the minor caudal artery traveled for the most 

 part dorsad of the caudal artery. In both Scorpaenichthys and 

 Clinocottus the minor caudal artery divides into a dorsal and a 

 ventral minor caudal fin artery (fig., 8 C.F.A.'n) and C.F.A."{x)). 

 As a rule these branches traverse the basal canal of the fin with, 

 but cfeudad of, the corresponding caudal fin arteries, and like them, 

 send off a branch, the minor caudal ray artery (fig. 8, C.R.A.d)). 

 These minor branches always fork before the caudal ray arteries 

 do, and like them follow the dorsal and .ventral surfaces of each 

 ray, but so far as could be determined they did not extend caudad 

 of the intrinsic muscles of the caudal fin. They appear, however, 

 to furnish the principle supply for these muscles; while the cau- 



