125 



artery, called by him the internal carotid, and two brbito-nasal arteries, 

 one on either side; but he states, in a foot note, that there are two 

 of these internal carotids in the fish, only one being shown in the 

 figure. 



Boulenger's figure of Gad us raorrhua, above referred to, is said to be 

 "altered from T. Jeffeey Parker," and in his figure, as in Parker's, an 

 artery is shown lying in and extending the full length of what is apparently 

 the hyoidean arch. This artery is called by both these authors the 

 hyoidean artery, and from it a branch is sent forward to supply the 

 pseudobranch, that organ being placed anterior to the hyoidean artery 

 at a distance from it about equal to the spaces that separate the branchial 

 arteries one from the other. This position of the pseudobranch, in the 

 somewhat diagrammatic figures, suggests that it is a mandibular 

 organ, but Parker definitely states (p. 103) that it is a "rudi- 

 mentary hyoidean gill", while Boulenger, although indicating the 

 organ by the index letters hy. ps., says that it is probably a spi- 

 racular pseudobranch and not a hyoidean one; the term "spiracular" 

 here apparently being used as equivalent to mandibular. Of the 

 arteries of the hyoidean arch in teleosts, Boulenger says (1. c. p. 336) : 

 "Both the proper afferent and efferent arteries of the hyoidean hemi- 

 branch either disappear or, as in the cod (Gadus morrhua), the effe- 

 rent artery may be represented on each side by an anastomosis between 

 the hyoidean artery and the cephalic circle." That this anastomosis Avith 

 the circulus cephalicus represents the efferent hyoidean artery is pro- 

 bably not correct, as will be later explained, and it will also be shown 

 that there is in Gadus, as in Esox and Salmo, a secondary afferent hyoidean 

 artery probably developed from a persisting ventral portion of the 

 posterior efferent hyoidean artery. 



Turning now to my specimen of Gadus aeglefinus, I find the 

 afferent arteries of the first and second branchial arches arising in- 

 dependently from the truncus arteriosus, the arteries of the third and 

 fourth arches arising either close together or as a single trunk. There 

 is no indication of an afferent hyoidean artery arising either from 

 the truncus arteriosus or from either of the first afferent branchial 

 arteries. 



The first and second efferent branchial arteries empty indepen- 

 dently into the lateral dorsal aorta, but the third and fourth arteries, 

 which in Gadus morrhua also empty independently into the lateral 

 dorsal aorta, first unite, in Gadus aeglefinus, to form a short but 



