310 
PACIFIC SCIENCE, Vol. IV, October, 1950 
Fig. 1. Outline of head region of Kaupichthys 
diodontus indicating the course of the lateral line 
canals. Areas in which the canals pass through 
flesh are shown as dotted lines; areas in which 
canals pass through bone are shown in dashed lines 
with the outlines of the bones drawn in. Pores 
opening to the exterior from the canal system are 
shown as circles, aa, Articular-angular; an, an- 
terior nostril; d, dentary; fr, frontal; go, gill open- 
ing; ic, infraorbital canal; 11, lateral line; pc, pre- 
opercular canal; pe, pectoral fin; pn, posterior nos- 
tril; po, preopercle; pt, pterotic; su, supraorbital 
canal; tc, transverse postcranial canal. 
ning up and across the nape just behind the 
skull connects the longitudinal canals of the 
two sides of the body; it gives rise to a series 
of pit organs externally but to no pores. The 
preopercular canal (pc) exits ventrally from 
the longitudinal canal opposite the junction 
of the latter with the one crossing the nape 
and proceeds anteroventrally through the 
preopercle and into the articular-angular and 
dentary in a normal manner. The longitu- 
dinal canal itself passes forward into the 
head as the supraorbital canal (su), which 
runs the entire length of the pterotic and 
through a short section of the frontal; from 
here it passes forward in a tube — all that is 
left of the nasal — to the tip of the snout. In 
addition, a short branch runs mesially in the 
frontal, but does not meet its fellow from the 
other side, nor does it give rise to a pore to 
the exterior. The infraorbital canal (ic) 
emerges from the supraorbital system in the 
frontal, runs laterally and then downward 
behind the eye and finally forward in the 
upper lip to the tip of the snout; in the lip 
it runs mesial to the posterior nostril and 
below the anterior nostril. The pores open- 
ing to the exterior from the lateral line sys- 
tem are shown in Figure 1. 
The suspensorium of Kaupichthys (Fig. 2) 
is vertically suspended, i.e., the articulation 
between the quadrate (q) and the articular- 
angular (aa) lies but slightly behind the 
center of the hyomandibular ( h ) . The pala- 
topterygoid (pp) is laminar and well devel- 
oped for eels, but appears to be unattached, 
except by a ligament, either before or behind. 
The maxillary ( m ) articulates with the com- 
bined premaxillary, ethmoid, and vomer (ev) 
near the tip of the snout. The opercular 
apparatus is reduced. The preopercle (po), 
which remains chiefly as a tube for the lat- 
eral line canal, overlies the broadly wedge- 
shaped interopercle (io). The subopercle 
(sr) completely encircles the opercle (op) 
below. The top half of the normal fish oper- 
cle is gone, only the lower half remaining. 
Fig. 2. Head skeleton with suspensorium, jaws, 
opercular bones, and branchiostegal rays. Teeth 
are omitted, and all the branchiostegal rays are not 
shown: as, Alisphenoid; br, branchiostegal ray; 
ep, epiotic; ev, premaxillary-ethmo-vomer ; fr, 
frontal; h, hyomandibular; if, interorbital fora- 
men; io, interopercle; m, maxillary; op, opercle; 
os, orbitosphenoid; pa, parietal; po, preopercle; 
pp, palatopterygoid; ps, parasphenoid; pt, pterotic; 
q, quadrate; so, supraoccipital; sp, sphenotic; sr, 
subopercle. 
In the cranium (Fig. 3 a-d) the premaxil- 
la ries are ankylosed to the ethmo-vomer. The 
orbitosphenoid (or) is a long, slender bone 
wedged between the parasphenoid (ps) be- 
low and the alisphenoid (al) and frontal 
above. The enlarged otic bulla (ob) is com- 
posed ventrally of the basioccipital (bo) and 
the prootic (pr) ; it contains a large sagitta 
