th e anterior end of th e maxillary process of th e palatine. This process of the palatine is, as in Trigla,
closely bound to the dorso-mesial edge of th e lachrymal, and from th e adjoining edges of these two
bones a strong ligament arises and has its attachment on the dorsal surface of th e maxillary. This
ligament, as already stated, apparently represents th e distal half of th e rostro-palatine ligament
of Scorpaena. The ethmo-maxillary ligament is represented by a short ligament th a t extends from
th e ascending process of th e maxillary to th e ventral surface of the nasal, a t th e base of its processlike.
antero-lateral corner. There is no ligamentary process either on th e external or internal surface
of th e bone, this doubtless being in causal relation to the slightly developed condition of the maxillomandibular
ligament and of th a t tendon of the adductor mandibulae th a t has its insertion on the
maxillary.
The NASAL is a flat quadrilateral bone, which rests, in large part, directly upon th e dorsal
surface of th e th in flat anterior portion of th e antorbital cartilage. In the anterior two-thirds of its
length it suturates, in the middle line, with its fellow of th e opposite side. Posteriorly it diverges
slightly from th e middle line, leaving a V-shaped space between itself and its fellow of th e opposite
side, this space receiving th e pointed anterior end of th e m esethmoid. The narrow h ind end of th e bone
suturates with th e mesethmoid, slightly overlapping th a t bone externally. Laterally, th e posterior
half of th e bone suturates with th e long anterior end of th e ectethmoid, in th e manner already described.
The dorsal surface of this p a rt of th e bone is deeply grooved, near and parallel to its lateral
edge, for th e second p rimary tube of th e supraorbital lateral canal, as also already described. A narrow
wall of bone alone separates th e extreme anterior end of this groove from th e hind end of th e nasal
incisure. The antero-lateral comer of the bone is prolonged into a short s to u t horn-like process which
rests upon the summit of the anterior palatine process of the ethmoid cartilage. On th e lateral surface
of th e anterior end of this process there is th e large opening of th e anterior primary tube of the
supraorbital latero-sensory canal, this tube opening on th e outer surface b y a single large pore.
The bone is traversed by th e supraorbital latero-sensory canal, and lodges one organ of th e line.
The lateral half of th e nasal is thickened, its full length, and this thickening would seem to be
due to th e fusion, with th e usual dermal component of th e bone, of a th in underlying plate of bone.
This underlying plate lies directly upon th e cartilage of the snout, and projects slightly beyond the
overlying portion of th e nasal, both anteriorly and laterally. The laterally projecting portion of the
plate forms the floor of the nasal pit, while th e anteriorly projecting portion overlaps externally the
hind edge of the ascending process of the vomer. The antero-lateral corner of th e plate lies directly
beneath b u t is separated by a very narrow slit from th e process-like antero-lateral corner of the
dorsal, dermal portion of th e bone, and here approaches and gives support to th e base of th e b u t
slightly developed anterior palatine process of th e ethmoid cartilage. This la tte r process forms, as
in Trigla, th e antero-lateral comer of th e th in flat cartilage of the snout.
The ventral plate of the nasal of Peristedion th u s occupies somewhat th e position of th e corresponding
half of what I have described, in Trigla, as the perichondrial portion of the mesethmoid
of th a t fish. I t also occupies much th e position of the plate th a t I have described, in Belone, as underlying
th e dermal component of the nasal of th a t fish. In Peristedion, as in Belone, it separates from
the underlying cartilage, in slightly boiled specimens, without breakage of th e cartilage, and hence
would seem to be of membranous origin, b u t this was n o t carefully investigated. Two suppositions
suggest themselves regarding it. The one, th a t there is a predisposition in the tissues of this region
to th e development of this plate, and th a t th e plate attaches itself to the mesethmoid or nasal,
according as th e one bone or th e other covers th e region; and the other, th a t the anterior palatine
process of the ethmoid needing support, a supporting plate is developed from the nearest bone
available.
The FRONTAL has nearly straight mesial and hind edges, lying a t a right angle to each other.
I t has a small v entral flange, resembling somewhat, b u t m uch smaller th a n th a t of Scomber. Posterior
to this flange, on the ventral surface of th e bone, there are two slight ridges, meeting a t an angle,
which form, as the similar b u t more developed ridges of Scomber do, the antero-mesial and anterolateral
boundaries of th e anterior end of th e lateral cranial fontanelle. The frontal suturates mesially
with its fellow of th e opposite side, posteriorly with the parieto-extrascapular, and laterally with
th e pterotic, the postfrontal, and a small corner of the sphenotic th a t comes to th e level of the outer
surface of th e dermal bones. I t is traversed by the supraorbital latero-sensory canal and lodges five
organs of th a t canal, which are similarly disposed to those found in Scorpaena and Trigla; th a t is,
th e second, third and fourth organs of th e line are in regular positions; the fourth and fifth organs lie
close together w ithout intervening primary tube; and th e sixth organ is a small one lying in th e small
terminal tube of th e line and innervated by a nerve th a t first issues in th e orbit and then perforates
th e alisphenoid to enter the cranial c avity and perforate the frontal b eneath th e organ i t innervates.
The POSTFRONTAL is a small bone th a t forms th e roof of th e small dilatator fossa, and is
bounded mesially by the frontal, posteriorly b y th e pterotic, and anteriorly by th e dorso-lateral
corner of th e sphenotic. I t is traversed by the dorsal end of th e postorbital portion of the main infraorbital
canal, and lodges one organ of th a t canal, innervated b y the ramus oticus lateralis.
The PARIETO-EXTRASCAPULAR forms p a rt of the hind edge of the secondary skull, and its
hind edge is thickened and grooved, as already described. The bone suturates anteriorly with the
frontal, and laterally with th e pterotic, lateral extrascapular, and suprascapular, not overlapping
dorsally the epiotic process of th e la tte r bone. I t lies directly upon the supraoccipital, the epiotic
and the adjoining cartilaginous portions of the roof of the cranium, its lateral edge forming p a rt of the
roof of th e temporal fossa. Its hind edge is traversed by the supratemporal commissure of the latero-
sensory system and lodges one organ of th a t commissure.
The LATERAL EXTRASCAPULAR is a small subcircular bone lying between th e frontoparietal
and lateral spinous ridges, wedged in between the pterotic, parieto-extrascapular and suprascapular
bones. I t forms p a rt of the roof of the temporal fossa, b u t does not come to th e lateral edge
of the skull, being shut off from th a t edge by relatively wide suturating portions of the pterotic and
suprascapular. I t is traversed by the lateral portion of th e supratemporal latero-sensory commissure
and lodges one organ of th a t commissure. I t is not perforated by th e main infraorbital canal,
as in the other fishes described, th e canal here simply passing along the lateral edge of the bone,
pa rtly enclosed in it, and there apparently being no organ of th e main infraorbital line related to it.
In this Peristedion resembles Dactylopterus, as will be later described.
The SUPRASCAPULAR forms the postero-lateral corner of the dorsal surface of the skull,
and the larger p a rt of the roof of th e temporal fossa. I t has a well developed opisthotic process, b u t
no differentiated epiotic process, th a t p a rt of th e bone th a t represents th a t process being relatively
short and appearing as an epiotic region ra th e r th an an epiotic process of th e large body of th e bone.
On the ventral surface of this epiotic region of th e bone there is ,a small ventral process, and this
process an d th e adjoining portion of th e mesial edge of th e bone suturate with the hind end of the
suprascapular process of the epiotic. The anterior edge of this p a rt of the bone suturates with the