The FRONTAL has a well developed ventral flange which comes into contact with th e ali-
sphenoid and sphenotic, and possibly also, in some specimens, with th e dorsal end of th e ascending
process of th e parasphenoid; b u t the exact relations of th e bones here could n o t be determined, for
their outlines were n o t distinct in either of my three skulls, and I could n o t disarticulate th é bones
in the one skull th a t I could spare for th e purpose. Posterior to this ventral flange, there is a smaller
flange on th e ventral surface of th e frontal, the two flanges embracing the dorsal edge of th e alisphenoid,
and the small posterior flange forming th e dorsal portion of a pa rtitio n between th e fore and midbrain
recesses of th e cranial cavity. The ventral flanges of the frontals of opposite sides are relatively
widely separated from each other and form the lateral boundaries of the dorsal portion of th e wide
orbital opening of th e brain case.
The frontal is bounded posteriorly by th e parieto-extrascapular and supraoccipital. Anterior
to th e la tte r bone it rests directly upon the postepiphysial cartilage, th is p a rt of th e bone, and also
th e p a rt th a t lies immediately anterior to it, being so th in as to be almost transparent. The hind
end of th e lateral edge of th e bone is bounded by th e pterotic, and anterior to th a t bone is in contact
with a corner of th e postfrontal.
The bone is traversed by th e supraorbital canal and lodges five organs of th a t line, a primary
tu b e leaving th e canal between each adjoining two of th e five organs. There is thus one tu b e more in
this fish th a n in Scorpaena, this seeming to confirm th e conclusion th a t a tube has disappeared in th e
la tte r fish, as already explained. The fifth frontal organ of Cottus, th e sixth one of th e line, lies in th e
small terminal tube of th e canal, is well developed, and is innervated by a branch of th e ophthalmicus
lateralis th a t pierces th e skull from th e outside and has an intracranial course, as in Scorpaena.
The penultimate, or sixth tube of the line anastomoses with th a t tube of th e main infraorbital canal
th a t lies between the postfrontal and pterotic.
The POSTFRONTAL has a postorbital position, and is, in appearance, the dorsal one of
two postorbital bones. This bone, however, lodges th e anterior one of th e two infraorbital sense
organs th a t are innervated by th e ramus oticus, th is definitely identifying it as a postfrontal. The
hind end of th e dorsal edge of th e bone lies on th e dorsal surface of th e sphenotic, the anterior and
larger p a rt of this edge of th e bone abutting against th e lateral edge of th e postorbital p a rt of th e
frontal.
The PARIETO-EXTRASCAPULAR is traversed, near its hind edge, by th e mesial section
of th e supratemporal latero-sensory canal, and bears a t its hind edge th e parietal spine. I t lodges
one organ of th e supratemporal commissure.
The LATERAL EXTRASGAPULAR is usually represented by two ossicles, one traversed
b y th e main infraorbital latero-sensory canal, and th e other by the lateral section of th e supratemporal
canal, b u t in one of the two fishes examined, th e two ossicles were fused to form a single bone.
The ossicle th a t lodges th e lateral section of the supratemporal canal bridges the temporal fossa,
th e o th e ï ossicle roofing th e lateral portion of th e postcommissural portion of the same fossa; the
commissural ossicle lying a t th e anterior end of the infraorbital ossicle. Each ossicle lodges a single
organ of the related latero-sensory line.
The SUPRASCAPULAR has a stout, pointed epiotic process which rests upon the dorsal
surface of th e suprascapular process of th e epiotic; and a short, stout and broad opisthotic process.
The la tte r process is directed downward and forward, its flat surface lying in a somewhat transversé
position, and, on one side of one of my three specimens, it almost entirely closed not only the
posterior b u t also th e lateral opening' of th e temporal fossa, leaving only small openings on either
side of it. On th e other side of th a t , one specimen, and on both sides of th e two other specimens, the
opening lateral to th e proeess was the larger of th e two, the opening mesial to the process being p ractica
lly closed in one;pi th e typi specimens. Mesial to the base of the opisthotic process there is, on the
under surface of the bone, an articular facet, and directly posterior to th e base of th e process there
is an articular eminence; th e two surfaces giving articulation to the supraclavicular. The body of
the bone is traversed by th e main infraorbital canal and lodges one organ of th a t canal, innerv
a ted by a branch of th e supratemporal branch of the nervus lineae lateralis. The bone is
w ithout spine.
The SUPRACLAVICULAR has, on th e anterior corner of its dorsal edge, a facet which gives
articulation to the articular eminence on the under surface of th e suprascapular. From the mesial
surface of this p a rt of th e bone a process arises, directed antero-mesially, and on its anterior end
i t has an articular eminence which articulates with the articular facet on th e suprascapular. The
dorsal edge of the bone is traversed by a short section of the main infraorbital latero-sensory canal
and lodges one organ of th a t line. The posterior comer of the bone is prolonged into the s to u t supra-
clavicular spine.
The PARASPHENOID has, on either side, a tall and broad ascending process with two dorsal
ends. These two dorsal ends are pointed and separated b y a large V-shaped incisure in my small
specimens, b u t bifid and separated by a shallow depression in th e large specimen used for illustration.
The posterior and shorter end, or point is directed toward, and nearly reaches the trigeminus foramen,
an d is in contact with and firmly bound to the prootic. The anterior and longer point is in contact
with and firmly bound to the alisphenoid, and almost, if n o t quite reaches in certain specimens the
ventral edge of th e ventral flange of th e frontal. These two ends, or points, belong respectively to
posterior and anterior portions of th e ascending process, and between the two portions the outer
surface of th e process is quite concave, its inner surface being correspondingly convex. Between
the posterior portion of th e process and th e body of th e parasphenoid there is a normal internal
carotid foramen.
On th e dorsal surface of the parasphenoid, between the bases of the ascending processes, there
is a raised median portion on th e dorsal surface of which there is a relatively large median pit, the
point of the p it directed downward and backward. The p it gives insertion to the recti interni muscles.
Immediately posterior to it there is a depressed region on th e dorsal surface of the bone, and then a
raised median rib, this rib lying between the ventral edges of th e prootics of opposite sides and
forming the median portion of the floor of the myodome.
The ALISPHENOID is bounded posteriorly by the sphenotic and prootic, with both of which
bones it is in synchondrosis. Antero-dorsally it is overlapped externally by the ventral flange of the
frontal, and ventrally it is in contact with th e anterior portion of the ascending process of th e parasphenoid.
I t has short b u t broad basisphenoid and parasphenoid legs, these two legs enclosing a
V-shaped groove which begins a t nothing, a t th e anterior end of the ventral edge of the bone, and
deepens gradually toward its hind end. The external bounding plate of this V-shaped groove is the
parasphenoid leg of the bone and is the p a rt of the bone th a t is in contact with the ascending process
of the parasphenoid. The internal bounding plate of the groove is the basisphenoid leg of the bone,