th e anterior prolongation passes along th e lateral surface of th e maxillary, process of the palatine,
and then turns mesially beneath th a t process, between i t and the lining membrane of th e roof o f
the mouth cavity, and abuts and terminates against th e lateral (distal) surface of th e ascending
process of the maxillary.
From th e mesial or dorso-mesial surface of the mesial leg of the U-shaped sac th e mesial diverticulum
has its origin, this diverticulum being formed of a noticeably delicate and very flexible membrane.
I t lies against th e lateral surface of th e rostral, has a short anterior prolongation between
the rostral and the mesial surface of th e ascending process of th e maxillary, and a longer posterior
prolongation which extends around th e hind end of th e rostral, and there meets, b u t in th e adult,
so far as could be determined by dissection, does not communicate with th e corresponding diverticulum
of th e opposite side. In 45 mm specimens th e diverticula are apparently here in large and
free communication with each other. From the disposition of the diverticula, it is evident th a t when
th e mouth is protruded and retruded the capacity of th e nasal sac is first considerably enlarged
and then diminished, the circulation of the water in it thus being facilitated, as Kyle has stated.
N A S A L .
The nasal is a small bone, which, by a downwardly projecting portion of its hind end, fits
against and is firmly attached to, th e lateral surface of th e mesethmoid process. I t encloses th e nasal
portion of th e supraorbital latero-sensory canal, and bears, on its hind end, th e nasal spine. From
its anterior end th e naso-maxillary ligament arises, and tunning forward and downward is inserted
on th e ligamentary process of th e maxillary. On its inner surface, near its hind end, and also on th e
adjacent ligamentary surface of the mesethmoid process, th e ethmo-maxillary ligament and th e
small rostro-nasal branch of th e large palato-rostral ligament both have their attachments
F R O N T A L .
The frontal touches, in th e mid-dorsal line, throughout nearly its entire length, its fellow
of th e opposite side. At its anterior end its lateral edge rests upon the dorsal surface of th e ecteth-
moid, its mesial edge resting upon th e dorsal surface of the pointed posterior portion of the mesethmoid.
In the anterior half of th e orbital region, its mesial edge rests upon the dorsal edge of th e
interorbital septum, th a t septum being a th in wall, cartilaginous in its anterior b u t membranous in
its posterior portion. In th e posterior half of th e orbital region a th in flange-like process has its origin
from th e ventral surface of th e frontal, th e line of origin of th e process running, a t first, backward
and b u t slightly laterally, and then turning laterally, in a rounded angle, toward the postorbital
corner of th e lateral edge of the bone. From this line of origin th e flange projects downward, backward
and mesially, beginning a t nothing anteriorly, increasing gradually in depth until it reaches the
rounded angle of its line of origin, and then diminishing again almost to nothing shortly before it
reaches th e postorbital comer of th e bone. The ventral edge of th e anterior half of th e flange, th a t
is, up to its deepest point, gives atta chm en t to th e dorsal edge of th e membranous posterior half of
th e interorbital septum; th e flanges of opposite sides, which touch in th e middle line throughout a
p a rt of th is distance, enclosing an -anterior portion of th e cranial cavity. Posterior to its deepest
point, th e flange, turning laterally, overlaps externally and lies closely against the external surface
of th e dorsal half of th e alisphenoid, th e base of the flange resting against th e external surface of the
line of cartilage th a t caps th e dorsal edge of th a t bone, and the body of th e frontal, immediately
postero-mesial to the flange, resting upon the dorsal surface of this same line of cartilage. Posterointernal
to this large flange and slightly postero-lateral to the antero-mesial end of th e line of alisphenoid
cartilage, a short narrow and pointed process projects downward from the ventral surface
of the frontal, lies against th e internal, postero-mesial surface of th e cartilage, and may even extend
ventral to th e cartilage, there lying against the corresponding surface of the alisphenoid. This little
process of the frontal, and th e large flange-like process of th e same bone, thus clasp and hold between
them the dorsal end of the alisphenoid, in a manner similar to th a t described by me for these same
bones in Scomber. From th e hind edge of the little process a delicate ridge runs postero-mesially
toward the postero-mesial corner of th e frontal. I t corresponds to th e flange th a t, in Scomber, forms
th e lateral boundary of the post-epiphysial cartilage, th a t cartilage being reduced, in Scorpaena, to a
narrow band along th e anterior edge of the supraoccipital. Postero-lateral to the alisphenoid, the
greatly diminished flange of th e frontal overlaps slightly, or abuts against, the dorsal edge of the
sphenotic.
The lateral edge of the frontal, a t and posterior to its postorbital corner, rests upon the dorsal
surface of th e sphenotic, th e mesial corner of its hind edge resting upon the dorsal surface of the
supraoccipital, and the hind edge of th e bone articulating by suture with th e anterior edges of the
pterotic and parieto-extrascapular. Adjacent to th e sphenotic and supraoccipital bones the frontals
each re st upon small cartilaginous remnants of the chondrocranium; and between these cartilages
and th e related bones, they form p a rt of th e roof of the cranial cavity, covering a large median opening
in th e roof of th e chondrocranium formed by th e fusion of th e anterior ends of th e lateral fontanelles.
This median opening is open anteriorly, there being no cartilaginous epiphysial ridge to form its
anterior boundary; Sagemehl’s statement th a t this ridge is found in all teleosts thus not being correct.
The frontal is traversed by th e supraorbital latero-sensory canal and lodges five organs of th a t
line, two of these organs, the 4th. and 5th. of the line, lying relatively close together, without an
intervening primary tube, as will be fully explained when describing the canals. The position of th a t
p a rt of th e canal th a t lies between th e orbits is marked by a strong ridge, already several times referred
to as th e frontal or interorbital ridge. A similar ridge marks approximately the position of th e fourth
tube of th e line; th a t tube running mesially and slightly backward to meet, in th e middle line, its
fellow of the opposite side. The hind edge of this ridge forms th e anterior boundary of the groove
on the vertex.
That p a rt of th e cranial cavity th a t is enclosed between the anterior halves of the ventral
flange-like processes of the frontals corresponds to the fore-brain recess of my descriptions of Scomber,
but, in Scorpaena, the cranial cavity is so large, relatively to the brain, th a t the fore-brain lies wholly
posterior to the recess, reaching, approximately, only to th e anterior edge of the basisphenoid. The
olfactory nerves there pierce th e membranes th a t close th e Crbital opening of the brain case, and,
enclosed in a membranous tube, traverse the orbit. The fore-brain recess of the adult Scorpaena
thus lodges no portion of the brain, being simply filled with fa tty tissue.
P O S T F R O N T A L .
The postfrontal is a small flat bone which lies directly upon, and is quite firmly bound to, the
posterior portion of th a t p a rt of the dorsal surface of the sphenotic th a t is n o t covered by th e frontal
and pterotic. Along its anterior and lateral edges, narrow strips of the sphenotic appear, and form
Zoologioa. I le f t 57. g