— 54 — 



skull, not, accordingly, traversing the so-called jugular foramen, which foramen is the facialis opening 

 of the trigemino-facialis Chamber of my descriptions. This course of these two arteries being so 

 unusual, I have had it looked up both in Rhombus and Solea. In both these fishes the efferent pseudo- 

 branchial artery runs forward external to the cranium, the external carotid traversing the trigemino- 

 facialis Chamber, both arteries thus having exactly the same general course that they have in Scor- 

 paena and that they are known to have in many other teleosts. That Pleuronectes forms an exception 

 to this rule I greatly doubt, the particular specimen examined by Cole & Johnstone doubtless pres- 

 enting an abnormality in the course of these two arteries, as it apparently does also in the absence 

 of an encephalic artery arising from the transverse commissure that is said to connect the internal 

 carotids of opposite sides. 



The internal carotid of Scorpaena, having given off the orbito-nasal artery or the communi- 

 cating branch to the efferent pseudobranchial artery, as the case may be, runs mesially and but 

 slightly anteriorly along the floor of the myodome, lying immediately beneath the rectus internus 

 muscle. Having reached the middle line of the head, the artery turns upward between the two recti 

 interna muscles, there lying closely pressed against its fellow of the opposite side. Whether there is 

 here an anastomosis of the arteries of opposite sides to form a single median encephalic artery, such 

 as Allen describes in Ophiodon, or not, could not be determined; but there probably is, as, other- 

 wise, there would be no circulus cephalicus in this fish. It may, however, here be stated that the 

 diagrams ordinarily given of this circulus, and as given by Ridewood ('99) for Cottus and Trigla, 

 are misleading, for there is not here a simple transverse commissure, such as there is for the efferent 

 pseudobranchial arteries. There are two arteries, one on either side, which, running upward to enter 

 the cranial cavity, lie close together and fuse in the middle line for a short distance, and then separate 

 again as they enter the cranial cavity. The one or two arteries in Scorpaena, whichever it be, running 

 upward enters the hind end of the median vertical band of fibrous tissue, already described, that 

 arises from the hind edge of the pedicle of the basisphenoid and ends posteriorly in the fibrous tissues 

 that close the pituitary opening of the brain case. Having traversed this tissue, the two arteries 

 become distinct again, perforate separately the membrane that closes the pituitary opening of the 

 brain case, along the hind edge of the basispheniod, and enter the cranial cavity, their further course 

 not being traced. 



In Scomber I have stated ('03, p. 93) that the internal carotid enters the cranial cavity along 

 the anterior edge of the basisphenoid, there perforating the membrane that closes the orbital opening 

 of the brain case. This marked difference in the relations of the artery to the basisphenoid, in this 

 fish and in Scorpaena, has led me to reexamine Scomber, and I find that my statement regarding 

 that fish is an error, the artery there running up posterior to the basisphenoid, as it does in Scorpaena. 



The vessel x was examined in sections of young specimens of Scorpaena, Trigla, Lepidotrigla 

 and Dactylopterus, but the results obtained were so unsatisfactory that I am preparing material 

 for a further study of it. It is so small a vessel that it was not looked for in any of the adults. 

 In the sections examined of Scorpaena, Trigla and Lepidotrigla strictly similar conditions were found, 

 while in Dactylopterus the vessel presented a slightly different arrangement. 



In Scorpaena, Trigla and Lepidotrigla the vessel is formed by the union of what seem to 

 be small arteries that arise in some sort of relation to the efferent arteries of the first three 

 branchial arches. Running forward parallel and close to the common carotid, the vessel soon 

 separates into two parts which may be called its internal and external branches. The internal branch 



