bone, and also on the mesial edge of the grooved portion posterior to it, rests the slender pointed
hind end of the posterior, process-like portion of th e lachrymal. This end of the lachrymal is grooved
on its dorso-external surface, and participates in th e articulation with the ectethmoid, the articulation
thus representing the lachrymo-ethmoid articulation of th e other fishes described. The dermo-
ectopterygoid, completely ankylosed with th e ectopterygoid, th u s fulfils th e function of th e posterior
ethmoid process of th e palatine of both Scorpaena and Trigla; b u t nevertheless th e bone does not
seem to be a palatine element, its relations to th e ectopterygoid being much more intimate th an
those to th e palatine.
The PALATINE is a slender rod of bone with an enlarged and flattened anterior end. The
ventral surface of th e hind end of th e rod-like portion of the bone rests against the dorso-mesial
surface of th e dermo-ectopterygoid, as ju s t above described. The lateral surface of this end of the
palatine, or th e lateral surface of th e covering dermo-ectopterygoid, and th e lateral surface also of the
anterior portion of th e palatine, rest against th e internal surface of th e posterior, process-like portion
of th e lachrymal, th e slit-like opening between these two surfaces of contact lodging the lateral portion
of the nasal sac. In the angle between the rod-like p a rt of th e bone and its enlarged anterior end,
on the mesial surface of th e bone, there is a concave articular surface, with a slight process a t its
anterior edge. This articular surface hooks around and articulates with th e anterior edge of the
little anterior palatine eminence of the ethmoid cartilage. Anterior to this articular surface, the
anterior end of the palatine widens, its mesial edge being slightly concave and its anterior edge
rounded and capped with cartilage. This p a rt of th e palatine forms its maxillary process, and fits
in th e depression and groove, already described, on th e ventral surface of th e base of th e spatulalike
anterior portion of the lachrymal. Between th e curved mesial edge of this maxillary process
of th e bone and the lateral portion of th e anterior edge of th e vomer, a semi-oval space is enclosed,
through which the ascending process of th e maxillary projects from below upward; this process of
the maxillary articulating by one surface with the vomer and by the other with the palatine, and
being bound to both bones b y connective tissue.
The OPERCULAR has th e irregular shape shown in th e figures. On the inner surface of the
anterior edge of th e bone there is a deep depression which receives th e opercular articular process
of th e hyomandibular. Dorso-posterior to this depression there is a larger depression on the inner
surface of a dorsal, process-like portion of th e bone, this depression giving insertion to th e adductor
operculi. Dorsal to th e surface of insertion of this la tte r muscle, in a narrow line along th e dorsal
edge of th e bone, th e levator operculi has its insertion. The dilatator operculi is inserted on the
anterior edge of th e bone, immediately lateral to th e articular facet for th e hyomandibular. On the
outer surface of th e bone there is a horizontal ridge which terminates posteriorly in a spine, this spine
being double in one of my specimens. Dorsal to this spine there is, on the hind edge of the bone,
a second spine.
The SUBOPERCULAR is a delicate bone th a t lies along th e inner surface of the hind edge
of the opercular, projecting dorsally beyond th e dorsal edge of th a t bone.
The I.NTEROPERCULAR lies along th e inner surface of the preopercular, considerably anterior
to, and wholly detached from th e opercular and subopercular. I ts antero-ventral end is slender and
rod-like, and almost reaches, and is bound by ligament to, th e hind end of the mandible. Its dorso-
posterior portion is flat and broad, and lies against and is firmly bound by ligament to th e lateral
surface of th e proximal end of th e ceratohyal, near the point where th a t bone articulates with the
interhyal; th e attachment apparently being to th e interhyal as well as to the ceratohyal. From
the dorso-posterior end of th e interopercular a stout ligament arises, and running dorsally, parallel
to and immediately posterior to the interhyal, is inserted on th e inner surface of th e preopercular.
The MANDIBLE is strongly curved a t its anterior end, to meet, in th e middle line, its fellow
of th e opposite side. Its middle point lies considerably posterior to the corresponding point of the
upper jaw, and th e dentary, like th e maxillary, the premaxillary, and th e vomer is wholly without
teeth. The articular has a pointed anterior end which projects slightly beyond the hollow of the
V between the dorsal and v entral limbs of th e dentary, and there lies internal to th a t bone. Posterior
to this point, th e ventral edge of this portion of the articular slightly overlaps, externally, the dorsal
edge of th e ventral limb of th e dentary. On the internal surface of the bone, posterior to the hind
end of Meckel’s cartilage, there is a slight eminence for the insertion of the tendon of a p a rt of the
adductor mandibulae muscle. The bone has a broad th in coronoid process. The angular is almost
completely fused with the articular, a sutural line on the external surface of th e bone alone indicating
its presence. The dentary has a long and slender dorsal limb which does not reach, by a considerable
interval, the dorsal end of th e coronoid process. On th e lateral surface of the dorsal edge of the
dentary, slightly anterior to the middle of its length, there is a dorso-laterally projecting shelf of bone;
and immediately beneath this shelf, on the external surface of th e bone, there is the large anterior
opening of a short canal which leads backward through the dentary into the ramus of the mandible.
This canal transmits a large nerve which goes immediately to the large barbel of th e fish, this barbel
having its attachment on the outer surface of the dentary in a pit-like depression th a t lies immediately
ventral to th e anterior end of th e projecting shelf of bone. On th e projecting antero-lateral comer
of this shelf of bone th e mandibular labial fold has its origin. The barbel of Peristedion thus arises
from th e mandible in th e place where th e gristle-like core of the mandibular fold of Scorpaena arises,
and, contiguous with it, th e m andibular fold has its origin. Whether this means th a t the core of the
mandibular fold of Scorpaena represents, or includes, the barbel of Peristedion, or not, I can n o t
determine.
The dentary and articular are both traversed by th e mandibular latero-sensory canal, the
d entary lodging three sense organs of th e line, and the articular one organ.
4. L A T E R O - S E N S O R Y C A N A L S .
The main infraorbital canal has the course already described through the infraorbital bones,
the lachrymal lodging four organs of the line, the second infraorbital bone one organ, the third bone
two organs, and the fourth and fifth bones one organ each; making nine organs in all in this p a rt
of the line, th a t being th e same number as in Trigla. The canal then traverses the postfrontal, in
which bone there is a single organ innervated by a branch of th e oticus lateralis, and then anastomes
with the penultimate tube of the supraorbital canal. The canal then traverses the pterotic, in which
bone there is a large pre-preopercular organ innervated by a branch of the oticus lateralis, and in
all probability a second and much smaller post-preopercular organ innervated by a branch of the
supratemporalis lateralis vagi. A branch of the la tte r nerve was found going to the canal in four
different specimens, b u t th e organ, if it exists, is so small th a t it could not be with certainty identified.
The canal anastomoses with the dorsal end of th e preopercular canal between these two organs.