'.14 



BULLETIN OF THE BUREAU OF FISHERIES. 



sei 1'iitl branches which supply the greater part of the musculus adductor mandibuhe: 

 the posterior branch (.9) runs ventrad and caudad, spreading out on the inner side of 

 the infra- and subopercular. 



Tk< afferent pseuJohraiwliidl /■<>*.* 7* (tigs. 1 and 6). Before entering the pseudo- 

 branch the hyoidean artery usually anastomoses with or is joined by one of two 

 arteries. The ordinary arrangement (tig. 1) is that where the hyoidean artery is 

 joined by a branch (20) of the a. hyoopercularis (17) and then enters the pseudo- 

 branch at its ventromedial angle to spread 

 out over the surface which adjoins the 

 hyomandibular bone. In the second 

 arrangement (tig. ti) the hyoidean artery 

 is joined, by means of a connecting branch 

 (IS), with a vessel which might be called 

 the direct afferent pseudobranchial artery 

 (12). 



B. The direct afft r. nip*, uddbranchial 

 artt ry (12) was present in only two of the 

 nine specimens dissected, and only on one 

 side. It was given oft' from the first 

 efferent branchial artery just lateral to the 

 carotid, and supplied the medial half of 

 the pseudobranch. It also anastomosed 

 with the hyoidean artery, and in this case 

 the latter supplied the lateral portion of 

 the pseudobranch. This arrangement re- 

 sembles that found in Gadus, as described 

 by Miiller (1839), where the pseudo- 

 branch receives its blood from the hyoi- 

 dean artery and from a branch which 

 comes directly from the circulus cephali- 

 cus. The former condition, which is the 

 one more generally met with among tele- 

 osts, resembles that described by Midler 

 for Sander (Znicioperca), in which the 

 pseudobranch receives blood from the' 

 hyoidean and hyoS'percular arteries. 



There appears to be considerable 

 variation among the teleosts with regard to the blood supply to the pseudobranch. 

 Aside from the two methods described above for the tile-fish, the pseudobranch of 

 teleosts in general receives its blood (a) entirely from the circulus cephalicus (pike. 

 according to Maurer, 1888); (b) entirely by the hyoidean artery (Spheroides, tig. 7): 

 or (c) by all three vessels — i. e., the hyoidean artery, a branch of the a. hyooper- 

 cularis, and the direct afferent pseudobranchial artery (Myoxocephalus, tig. 8). In 

 teleosts where the pseudobranch is wanting, the dorsal portion of the hyoidean artery 

 is reduced in size, as in Leptocephalus (tig. 2), where it terminates in branches which 

 supply the branchiostegal region and membranes at the dorsal end of the ceratohyal. 



Fig. 7. — Cranial portion of the arterial system in the swell- 

 fisb [Spheroides maculatus). Ventral view, natural size. 

 On the right side the ventral ends of the efferent branchial 

 arteries and their branches are reflected so as to bring 

 them into one plane. 



