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recess at the hind end of the fossa. The foramen opticum perforates 
the lateral wall of the fossa near its anterior end, as shown by GEGEN- 
BAUR, and the pituitary canal (canalis transversus) lies wholly in the 
cartilage of the basis cranii, dorso-posterior to the extreme hind end 
of the fossa, in much the position that GEGENBAUR shows it. The 
internal carotid canal of either side begins at a foramen near the 
middle line of the ventral surface of the chondrocranium, and running 
antero-mesially soon fuses with its fellow of the opposite side to form 
a short median and nearly vertical canal which runs upward in the 
cartilage, antero-ventral to the pituitary canal, and then separates 
into two branches, one on either side. Each artery then runs dorso- 
anteriorly, partly in the cartilage and partly between the cartilage 
and the tough lining membrane of the cranial cavity, until it receives 
the efferent pseudobranchial artery, when it soon pierces the overlying 
membrane and definitely enters the cranial cavity. The course of the 
artery in Acanthias vulgaris is probably strictly similar to that just 
above described, but GEGENBAUR’S figure of a median section of this 
fish shows the canal as a simple transverse canal, this being doubtless 
due to the median section of the skull having traversed the short 
median vertical section of the canal. 
The orbital opening of the pituitary canal, in Acanthias blain- 
villii, lies in the anterior portion of a deep trigemino-pituitary fossa 
at the hind end of the orbit, the foramen trigeminum lying imme- 
diately dorso-posterior to it in the same fossa; this fossa having the 
position of the foramen trigeminum of GEGENBAUR’S figure of Acan- 
thias vulgaris. Antero-ventral to this fossa there is the small foramen 
for the efferent pseudobranchial artery, this foramen having the 
position of the opening of the pituitary canal (canalis transversus) 
in GEGENBAUR’S figure, that author having possibly wrongly iden- 
tified this foramen. On the anterior edge of the trigemino-pituitary 
fossa there is a short, laterally projecting process of cartilage which 
lies directly against the posterior edge of the orbital process of the 
palato-quadrate and quite unquestionably represents the eye-stalk, 
this stalk here being greatly reduced in length, doubtless because 
of the position of the orbital process, which in this fish articulates 
with the extreme posterior portion of the mesial wall of the orbit. 
From the outer end of this short process the recti superior, inferior 
and internus muscles have their origins, the rectus externus having 
its origin entirely within the pituitary canal. The position of this 
