OF THE MARSIPOBRANCH FISHES. 
429 
points of cartilage cut through where the two systems of extra-branchials conjugate, 
below, were only figured in three places, in front (fig. 1 , ex.br.). 
Two partial vertical sections are figured, one (Plate 15, fig. 9) near the mid line, 
the other (fig. 8) more to the side. In the one nearest the middle (fig. 9) the fore 
part of the notochord is shown bent upwards, the cephalic part being enclosed in hard 
cartilage. The posterior nasal canal ( p.n.c.) ends beneath its front spinal region ; that 
pouch is seen to have a valvular fold inside it. 
Under the pouched end of this canal, the buccal cavity is partly shown, with a 
small tract of the facial cartilage between it and the branchial canal; and another 
small point of cartilage is caught in this region, namely, part of the skeleton of 
the “ intervelar shelf.” The fore part of the branchial canal ( br.c.) is exposed 
beneath the valvular end of the posterior nasal canal, and in it two oval internal 
branchial passages, and a small valvular pouch in front, at a lesser distance from the 
first opening than from the second. These are, in truth, the first three clefts, but the 
foremost, or liyomandibular opening {cl 1 .), does not pass through the wall of the head, 
and has developed very little since it first appeared. Evidently, it never quite closed 
up, or, if it did, it opened again during metamorphosis. In the more lateral section 
(Plate 15, fig. 8) the investing mass shows more in the cranial end of the notochord 
(nc., iv), and beyond it, in front of the posterior nasal canal [p.n.c.), the basis cranii 
is seen. Here we have the same openings—the first closed, and the two next open 
clefts, and in front of these the folds of the velum (vl.), and part of the frimbriated 
“intervelar shelf.” Between the lateral and sub-lateral filaments of the shelf there 
is seen a deep pyriform recess, this is the lateral buccal pouch (to the right of bp.), 
a diverticulum of the oral mucous membrane in front of the pharynx. It will be seen 
that the food-pharynx is not figured in these two sections, they were made beyond 
or outside the wall of this narrow tube (see Plate 23, figs. 1 and 4, phx.). The main 
crus of the one side of the intervelar skeleton is cut through (fig. 8, vl.). 
B. —Horizontal sections. 
' 
These sections help us to understand this peculiar type of cranio-facial skeleton. In 
the higher of the two (Plate 23, fig. 3) we see the eye-balls (e.) cut through their 
middle, and also the auditory capsules (cm.) in which the multilocular membranous 
labyrinth of each side is laid open. In front, the ethmoid [eth.) is cut across in 
its most solid part, and behind it, we see the outer nasal opening [e.n.) cut down close 
to the capsule (ol.), and in front of the ethmoid, part of the 2nd lateral labials are 
seen. Behind the nasal capsule we see the fore brain (C 1 .) and the cranial side walls 
( o.s .), which are sinuous and out-turned at each end, with the orbital muscles and 
eye-ball (e.) attached. Part of the pedicle is seen confluent with the auditory capsule 
(au.) ; the latter is open on the inner side for the entrance of the auditory nerve. The 
MDCCCLXXXIII. 3 Iv 
