224 EDWARD PHELPS ALLIS, JR. 
with the present work. The fact that, in one of my two speci- 
mens of Hyodon, it perforates the basisphenoid, is peculiar, and 
it is to be noted that in that specimen this bone has a greater 
anteroposterior extent than in the other, extending posteriorly 
beyond the sutural line between the alisphenoid and prootic, 
instead of ending anterior to that line, as in the other specimen. 
This, when compared with the conditions in the other fishes ex- 
amined, to be described later, would seem to indicate that the 
basisphenoid of Hyodon is not strictly comparable to that bone 
in those other fishes. 
On one side of my 51l-mm. specimen of Hyodon the efferent 
pseudobranchial artery entered the ventral compartment of the 
myodome with the internal carotid, through the foramen for 
that artery. On the other side it perforated the ascending proc- 
ess of the parasphenoid anterior to the internal carotid, sepa- 
rated from it by a narrow column of bone. Having entered the 
ventral compartment of the myodome, in its subpituitary por- 
tion, it passes ventral to the orbitonasal artery and is connected 
with its fellow of the opposite side by a cross-commissural ves- 
sel which passes anteroventral to the internal carotids. The 
efferent pseudobranchial artery then itself runs outward into the 
orbit, as the arteria opthalmica magna, to enter the eyeball and 
there supply the chorioid gland. 
In this 5l-mm. embryo, as in the adult, the alisphenoid bone 
has no pedicel (parasphenoid leg), this pedicel being represented 
by membrane only, as it is, wholly or in part, in many other Tele- 
ostei (Allis, 09). The pedicel or so-called vertical descending 
process (Ridewood) of the basisphenoid is also wanting, as al- 
- ready stated, that bone being represented by its horizontal plate 
alone. In those Teleosts in which this bone has a pedicel, its 
hind edge forms the median vertical anterior boundary of the 
myodome, and the anterior edge of the median vertical myo- 
domic membrane is attached to it. When the pedicel is want- 
ing, as in Hyodon, the vertical myodomic membrane runs in- 
sensibly into the membranous interorbital septum, and there 
is nothing to mark definitely its anterior limit. 
