course, the arte ry passes along the inner surface of the external one of th e two flanges on the hind
edge of the metapterygoid, there lying along the anterior edge of a p a rt of the levator arcus palatini
muscle th a t here has its insertion, and reaches th e ventral edge of the internal one of the two flanges
on th e metapterygoid. There it turns sharply dorso-posteriorly, crosses the internal surface of the
hyomandibular and enters the opercular hemibranch a t about its dorsal third. At th e bend it fuses
with the ventral end of th e external carotid, th a t artery forming, in direction, a direct dorsal continuation
of th a t p a rt of the arteria hyoidea th a t lies below the bend.
Allen (’05), in his work on Ophiodon, considers th e hyoid arte ry as ending a t th e point where the
mandibular arte ry is given off, th e arte ry above th a t point being called by him th e external carotid,
with an afferent pseudobranchial branch arising from it. This manner of naming these arteries is
based on the fact th a t, in Ophiodon, the so-called external carotid is so large, and th e hyoid artery
so small, th a t the flow of blood is said to be largely or wholly downward to the point where th e mandibular
arte ry arises, instead of upward from there, toward th e hemibranch. In Amia, also, I was
led to conclude (’00 c, p. 121) th a t th e flow of blood in th e dorsal portion of the a rteria hyoidea must
be downward, and be derived from th e carotid through th e pseudobranch. B ut granting th a t this
be so, th e nomenclature seems to me a faulty one, for th e artery, up to th e hemibranch, is certainly,
in its development, th e afferent pseudobranchial artery, or arteria hyoidea. Furthermore th e course
of this so-called p a rt of th e external carotid artery, as given by Allen in Ophiodon, is n o t exactly the
same as th a t of th e corresponding artery in Scorpaena, the artery being said b y Allen (1. c*, p. 51) to
pass „over the dorsal edge of the hyomandibular“ , then, „along the inner side of the m etapterygoid“
until it receives th e hyoid artery, after which it „comes to the outer surface through a foramen
between th e symplectic, hyomandibular, preopercular, and quadrate bones“ . In Scorpaena, this
p a rt of th e external carotid of Allen’s nomenclature passes downward between two flanges on the
hind edge of the metapterygoid, then comes to th e outer surface of the palato-quadrate through a
small foramen between the metapterygoid and hyomandibular, and, remaining always on the outer
surface of th e apparatus, receives th e hyoid-artery which passes outward through an opening between
th e symplectic, quadrate and preopercular to join it. And in Cottus, Trigla and Dactylopterus
strictly similar or equivalent conditions are found, as will be later described. In Scomber, also, this
a rte ry has the same course as in these several fishes : for, the connection of th e external carotid and
hyoid arteries not being given in my work on Scomber, I have had Mr. Henry examine it, in th a t
fish, and he finds the arrangement exactly as above described for Scorpaena, excepting th a t the
two sharp bends found in the hyoid artery (my nomenclature) of Scorpaena do n o t exist in Scomber;
th e arte ry in the la tte r fish having a nearly straight course as it runs upward from the hyoid arch
toward the opercular hemibranch, and th e external carotid falling into it a t a right angle. This course
of the artery in these several fishes seeming to make its course in Ophiodon exceptional, unless there
were some error or misconception of its course in Allen’s work, I had Mr. Allen reexamine it — for
he was a t th e time attached to my laboratory ^ and th e sketch sent me by him shows th a t the
conditions in Ophiodon are similar to those in Cottus; th e hyoid arte ry (my nomenclature) passing
to the outer surface of the palato-quadrate apparatus between the symplectic and preopercular, then
crossing th e external surface of the hyomandibulo-symplectic cartilage and passing to th e inner
surface of the apparatus again between th e hyomandibular and metapterygoid, Then the artery,
to all appearance, runs upward along the inner surface of th e hind edge of th e metapterygoid
as i t does in Cottus; but, in Ophiodon, the two flanges on th e hind edge of the metapterygoid
m ust He, as they do in Cottus, and as will be later described, in practically th e same plane, the internal
flange lying wholly dorsal to th e external one and th e adjoining edges oi th e two flanges being fused
excepting where th e y enclose a relatively large foramen which perforates th e bone so formed. The
hyoid artery, in Ophiodon, when it reaches the inner surface of th e palato-quadrate, accordingly
lies along th e inner surface of what is, in reaHty, the external flange on the hind edge of the metapterygoid
and not along the inner surface of the body of th a t bone. There it receives the external
carotid arte ry (my nomenclature) which, coming down along th e external surface of the internal
flange on th e hind edge of the metapterygoid, traverses the foramen between the ventral edge of th a t
flange and th e dorsal edge of th e external flange. This is also the condition found in Cottus, and
Allen’s description of Ophiodon is here so particularly referred to simply because it is another of
th e numerous instances th a t show th a t when existing descriptions seem to indicate th a t important
structures, in different animals, differ in th e ir relations to each other, reexaminations and a proper
understanding of the parts almost invariably show th a t such is not th e case. There are however
instances th a t do not seem capable of this interpretation. In Triton, for example, Coghill (’06) says
th a t th e ramus ophthalmicus profundus V passes dorsal to the ramus superior II I, while in Ambly-
stoma i t passes ventral to th a t nerve. The supposition th a t the ophthalmicus V is a superficialis in
Triton and a profundus in Amblystoma seems unwarranted, and even this would not explain the
conditions found in one specimen of Triton, where Coghill says th a t the ophthalmicus V passes b e tween
two portions of th e r. superior I I I , lying dorsal to one of them and ventral to the other.
In Scorpaena, the internal carotid artery, having separated from th e external carotid, runs
forward and downward in the groove on th e outer surface of the prootic, and, traversing the internal
carotid foramen enters the myodome across the internal carotid incisure. There it immediately
gives off a branch which, on one side of the 45 mm specimen examined, is small, runs forward in the
myodome and could there be traced b u t a short distance. On the other side of this specimen the
branch is large, runs forward in the myodome along the internal surface of the ascending process
of the parasphenoid, and, a t the anterior edge of th a t process, sends a branch toward the efferent
pseudobranchial arte ry (arteria ophthalmiea magna), apparently joining it, and then continues
forward as the orbito-nasal arte ry of Allen’s descriptions of Ophiodon. This connection of these two
arteries, if it actually exists, which could n o t be definitely established, would agree with th a t
found by me in Amia. I t was not found by Allen in Ophiodon (1. c., p. 55).
The efferent pseudobranchial artery arises from th e opercular hemibranch and, running forward
external to the cranium, terminates in the choroid gland of the eye-ball. Immediately anterior
to th e ascending process of th e parasphenoid, and immediately anterior also to the point where, on
one side of my specimen, the arte ry apparently receives a communicating branch from the internal
carotid, it sends a branch downward and mesially, across the ventral edge of the rectus internus
and dorsal to the parasphenoid,1 to :join, in the middle line, a corresponding branch from the
a rte ry of th e opposite side; a transverse commissure between the two arteries thus here being formed.
The efferent pseudobranchial a rte ry of Scorpaena thus differs in no respect from th a t in Ophiodon
excepting th a t, on one side of my specimen, i t apparently receives a communicating branch from
th e internal carotid.' ^
In I’leuronectes, Cole and Johnstone (’01, p . 96) say th a t the two ophthalmic (efferent pseudobranchial)
arteries: „perforate the prootics together with the superior jugular veins, passing through
th e jugular foramina“. The external carotids are said to break up along the ventral surface of the