imens examined, with the double dendritic system formed where the terminal tube of th e preopercular
canal anastomoses with the main infraorbital; a second, or th ird secondary connection thus
here being established between these two canals.
Beyond the 8 th. dendritic system the canal enters and traverses the postfrontal, .at th e hind
end of which bone it anastomoses with th e penultimate tube of th e supraorbital canal, a small double
system here arising from th e canal. The canal then tu rn s backward and traverses th e pterotic, a t
th e hind end of which bone it anastomoses with th e dorsal end of the preopercular canal, giving rise
to a double system, 10 inf.-12 pmd. This double system had, in the one satisfactory dissection
made, separated into two parts, one lying dorsal and th e other ventral to the main infraorbital canal.
The dorsal one of these two portions was small, and opened on th e outer surface in a small group
of pores, the ventral one being large and undergoing anastomosis not only .with the 8 th. infraorbital
system, as above described, b u t also with the 11th. system of th a t same line. This la st anastomosis
gives rise to a large and complicated system which spreads backward in the dermis th a t covers the
levator operculi muscle, extending even beyond th a t muscle onto th e dorsal portion of th e outer
surface of th e opercular.
Posterior to the 10 th. tube of the line, the main infraorbital canal traverses the lateral ex tra scapular
and then the suprascapular and supraclavicular, the 11th. tube of the line being given off
between the first two bones, th e 12 th. tube between th e la st two, and th e 13 th. tube a t th e hind
end of th e supraclavicular. The 11 th. tube gives rise, as ju s t above stated, to a large dendritic system
which anastomoses with th e ventral half of the double system 10 inf.-12 pmd. The 12 th. and
13 th. systems are small.
In th e full length of th e main infraorbital canal there are twelve sense organs, one organ thus
being found between each two consecutive primary tubes. Three of these organs lie in th e lachrymal,
one in the first suborbital, two in th e second suborbital, one in th e postorbital ossicle, and one each
in th e postfrontal, pterotic, lateral extrascapular, suprascapular and supraclavicular. The first six
organs of th e line are each innervated by consecutive and independent branches of th e ramus buccalis
facialis. The eighth (postfrontal) and ninth (pterotic) organs are innervated by branches of the ramus
oticus facialis. The innervation of th e 7 th., or postorbital organ could n o t be determined either
in the sections or the dissections, b u t it is quite unquestionably innervated by a -nerve th a t corresponds
to th a t somewhat independant branch of the buccalis th a t innervates, in Amia, th e posterior
group of buccal organs of th a t fish. If this be so, th e postorbital break in the main infraorbital canal
occurs between two groups of organs of the line, a n d is strictly similar to th e break found in this
same line in Batrachus ta u (Clapp, ’98) and Chimaera monstrosa (Cole, ’96), and to which I have
made full reference in several of my works.
The 10 th. (extrascapular) and 11th. (suprascapular) organs are innervated by branches of
th e supratemporal branch of th e nervus lineae lateralis vagi; the 12th. (supraclavicular) organ being
innervated b y the first single branch of th e la tte r nerve.
The supratemporal canal arises from the main infraorbital canal as th a t canal traverses the
lateral extrascapular. Running mesially it traverses the lateral extrascapular and then the parieto-
extràscapular, and then unites, in the mid-dorsal line, with its fellow of the opposite side, thus
forming a complete cross-commissure. As the canal passes from the lateral extrascapular into the
parieto-extrascapular it gives off a primary tube which separates into two parts one directed anteriorly
and the other posteriorly and both giving rise to relatively important dendritic systems. A similar
system arises where the canals of opposite sides anastomose in the mid-dorsal line. The canal contains
two sense organs, one lying in the lateral extrascapular and the other in the parieto-extrascapular;
both organs being innervated by branches of the supratemporal branch of the nervus lineae
lateralis vagi.
The supraorbital canal begins a t the anterior end of the nasal, traverses th a t bone, and then
runs backward in the frontal nearly to its hind edge. The anterior dendritic system of th e line lies
a t the anterior end of the nasal and is represented by a small and somewhat scattered group of pores.
The 2 nd. system of the line arises from the canal as it passes from th e nasal into the frontal. I t is
larger th an the first system and sends a long branch laterally and downward in the dermal bridge
between th e two nasal apertures. This branch opens on the outer surface by several pores, and in
one specimen, as already stated, one of these pores seemed to have anastomosed with a pore or pores
of the anterior dendritic system of the main infraorbital line, thus here establishing a connection
between these two lines. The 3rd., 4 th . and 6 th . systems all arise from th a t p a rt of th e canal th a t
lies in th e frontal, th e canal then ending while still in th a t bone, in the 7 th. or terminal system of
the line. The 5 th. system, which should normally be formed between the 4 th. and 5 th. organs
of the line, is wholly wanting even in the young specimens examined in sections. The tru n k of the
3rd. system is directed forward, and branching gives rise to an elongated group of from twelve to
eighteen pores. The tru n k of the 4th. system is d irected postero-mesially and traverses th e frontal to its
mesial edge, where i t anastomoses with its fellow of th e opposite side to form the frontal (supraorbital)
cross-commissure. The single median pore here first formed by th e fusion of the single primary
pores of ^.opposite sides has, b y subsequent division, given rise to a small median group of pores.
The tru n k of the 6 th. system runs postero-laterally in the frontal, to its lateral edge, where it
anastomosed with th e 9 th. tru n k of the main infraorbital to form a double system. Having given
off this trunk, th e canal tu rn s posteriorly and issues from the frontal beneath the frontal spine,
th e 7 th. or terminal system of the line being represented by a circular group of some ten to
fifteen pores.
The supraorbital canal contains six sense organs, this being one more th an is warranted by
the number of dendritic systems actually found in the fish. One of these organs lies in the nasal, and
five in th e frontal. The organ in the nasal is normal in its relations to th e trunks of the dendritic
systems, as are also th e first two organs in th e frontal; one of these la tte r organs lying between the
trunks of th e 2 n d . and 3 rd . systems of the line and the other between the trunks of th e 3 rd . and
4 th. systems. The fourth organ lies partly opposite and pa rtly posterior to the tru n k of the 4 th.
system, th e fifth organ being similarly related to th e tru n k of the 7 th. or terminal system. The
sixth organ is a small one lying in th e tru n k of th e 7 th. or terminal system of the line. Between the
fourth and fifth organs there is no primary tube in Scorpaena, b u t both in Cottus scorpius and
Cottus octodecimospinosus there is here a small tube. As, otherwise, the organs and tubes are exactly
similar in th e three fishes, a tube has certainly either aborted or never been developed, in
Scorpaena, between the fourth and fifth organs of the line. These two organs lie quite close together
and are innervated b y branches of a single branch of the ophthalmicus lateralis, the other organs
of th e line all being innervated by independent branches of the same nerve. The nerve th a t innervates
organs 4 and 5 perforates the frontal, a t th e base of its ventral flange, to reach the organs it
supplies, sometimes separating into its two parts external to the frontal and sometimes while tr a versing
th a t bone. In one young specimen examined in serial sections the branch to organ 5 separated