tions with these two ganglia th a t they do in Scorpaena, b u t they here both lie along the external
surface of the prootic.
There is thus, in Cottus, no bony trigemino-facialis chamber, th e outer wall of th a t chamber
being represented by membrane only, as it is in the 44 mm and 65 mm specimens of Scorpaena. But
singularly enough, th e outer wall of the internal jugular canal, which canal is simply an anterior
prolongation of th e trigemino-facialis chamber, has been ossified in Cottus, while in Scorpaena it
is almost wholly membranous. In th e specimen of Cottus used for th e figure, two little eminences
on th e outer surface of the prootic indicate a partial ossification of the outer 'wall of the trigemino-
facialis chamber. In th e other two of my three specimens these eminences did n o t exist, th e bone
there being simply slightly hollowed where th e trigemino-facialis foramina perforated it.
The prootic of Cottus has a perfectly normal mesial process, connected, by intervening cartilage,
with its fellow of the opposite side. The prepituitary portion of the process is short, not reaching
th e middle line. The pitu ita ry opening is thus not closed anteriorly by bone, and so forms an apparent
p a rt of the large orbital opening of the brain case. The membrane th a t closes the la tte r opening
is greatly thickened in the optic and basisphenoid regions, and there becomes a thick, tough, fibrous
structure the lateral edges of which are attached to both edges of the internal jugular recess. The
nervus oculomotorius pierces this membrane, on either side, near its lateral edge and enters th e myodome,
lying, in this p a rt of its course, between the ascending process of the parasphenoid and the
basisphenoid' membrane, and hence morphologically between th e two legs of the alisphenoid; its
normal position. A median, encephalic artery, formed by the union of th e internal carotids of opposite
sides, pierces the membrane near th e anterior edge of th e membranous p itu ita ry fossa, and enters
the cranial cavity.
The MYODOME is well developed; and it would seem as if th e skull of this fish must have
been unknown to Cope when he placed the Cottidae among those fishes in which the canal is wanting.
The hind end of th e canal is continued a short distance in th e basioccipital, b u t it does n o t open
posteriorly on the outer surface of the skull.
The PTEROTIC presents no features differing especially from those of th e bone in Scorpaena,
excepting th a t it lodges two sense organs of the main infraorbital line, one innervated by th e ramus
oticus and th e other by the supratemporal branch of the nervus lineae lateralis vagi; thepreoperc-
ular canal joining the main infraorbital between these two organs. The bone accordingly contains
a post-preopercular latero-sensory ossicle, this ossicle n o t being found in either Scorpaena or
Sebastes.
The BASIOCCIPITAL is much less deeply and extensively grooved by th e posterior portion
of th e myodome th a n in Scorpaena, and the cavum sinus imparis is simply a shallow depression.
The bone forms p a rt of the boundary of the foramen magnum, as in Scorpaena, and otherwise
resembles the bone in th a t fish.
The EXOCCIPITAL is perforated by three foramina, as in Scorpaena, b u t th e occipital
foramen is very small and represents a p a rt only of th e foramen of Scorpaena; a deep incisure in
th e hind end of the exoccipital, immediately dorsal to th e base of its condylar process, transmitting
th e larger p a rt of th e nerves th a t traverse the occipital foramen in Scorpaena. The bone, as in Scorpaena,
has a mesial process, which rests on the dorsal surface of the basioccipital and roofs the hind
end of the saccular groove.
The EPIOTIC has on its posterior surface, an epiotic ridge, which projects postero-laterally
to an unusual extent and nearly meets the opisthotic process of the suprascapular; thus nearly or
even quite closing the posterior opening of the temporal fossa.
The SUPRAOCCIPITAL has dorsal and ventral limbs, the former of which is largely
exposed, on the dorsal surface of the skull, between the frontals and parieto-extrascapulars. The
hind edge of th e dorsal limb projects backward, forming a short horizontal plate-like process
which slightly overhangs the ventral limb and rests upon, and is fused with, the dorsal
edge of the spina occipitalis.
2. I N F R A O R B I T A L B O N E S .
The infraorbital bones are, as in Scorpaena, four in number; a lachrymal, two suborbitals,
and a postorbital.
The lachrymal is concave on its outer and convex on its inner surface. I t has a short anterior
edge, the ventral half of which lies upon the lateral edge of th e broad anterior end of the maxillary
process of the palatine, and is very firmly bound to it by tissue. The dorso-anterior corner of the
bone bears, on its dorsal edge, a large concave articular facet which articulates with the articular
head on the ventral edge of the lateral process of the ectethmoid. The mesial edge of this facet is
greatly thickened and forms a s tout process projecting mesially, the outer end of which is deeply
grooved. The ventro-anterior surface of this process is rounded, and fits against and is firmly bound
to th e bottom of a unshaped depression on the external surface of the palatine; some slight motion
being possible between th e two pieces. The groove on the outer edge of the process is presented
posteriorly, is free, and simply gives attachment to tissues of the region. The bone lodges two sense
organs of the main infraorbital line, instead of three as in Scorpaena, the third and fourth organs
of the line here both lying in the first suborbital.
The first suborbital is a short and irregular bone, and lodges two sense organs, instead of a
single one, as in Scorpaena.
The. second suborbital is long and extends backward to the anterior edge of the preopercular,
either touching, or almost touching th a t bone, and being bound to it by tissue. A broad, low and
rounded ridge extends the full length of its outer surface. The main infraorbital canal traverses the
anterior two-fifths of the bone in a nearly horizontal position and then turns abruptly upward to
enter the postorbital bone, giving off a t the bend a short tube directed ventro-posteriorly, this tube
being double in the specimen used for illustration. The bone lodges two sense organs, one lying
anterior and the other posterior (here dorsal) to this tube. The posterior three-fifths of the bone,
and the ridge on its outer surface, are thus not developed in any apparent relation to any of the tubes
of the latero-sensory canal.
The postbrbital bone is bound to the dorsal edge of the second suborbital a t about th e anterior
two-fifths of its length, and it and the postfrontal form a slightly curved line which is convex anteriorly
and d irected upward and backward to join the dorso-lateral edge of the skull a t the sutural line between
the frontal and pterotic. The two bones lie slightly posterior to the orbit, the hind edge of the orbit
being formed by a stiff membrane th a t is attached to th e anterior edges of the two bones. The postorbital
lodges a single latero-sensory organ.