OF THE MARSIPOBRAHCH FISHES. 
397 
formed by the passing of the symplectic into the 1st epi-branchial (sy., e.br 1 .) ; this bar 
becomes dilated behind, has a sinuous margin in front, and sends backwards two sharp 
spikes or rays (non-segmented branchial rays). But this enclosing arcuate spiked bar is 
only the middle of the large 1st branchial arch ; it has a very long pharyngo-branchial 
piece above ( p.br h) and a long slender cerato-branchial (c.br.) below, both these rods are 
directed backwards and end in long, sharp styles, and both are ^shaped ; the lower 
is a part nearly segmented off from the rest of the basket-work, still it is attached, 
below, to the basal bar, behind the descending hyoid. The 1st pharyngo-branchial (jp.br 1 .) 
can be seen from the side filling in the hind and lower part of the middle fenestra, and 
serving to give “ origin” to a fan-shaped series of muscular fasciculi (Plate 16, fig. 1). 
That part is confluent with the hyomandibular, and is hard ; the rest is soft cartilage 
and passes upwards a little, and then directly backwards, being enclosed in the edge of 
the “velum” (Plate 16, fig. 6 ; and Plate 17, fig. 1, vl.). These sigmoid rods are con¬ 
tinuous on their inside, a little in front of their middle, with the fore end of another 
pair of rods, similar but smaller, and their serial homologues; these are the 2nd 
pharyngo-branchials (Plate 17, figs. 2, 3, p.br 2 .) ; they have no descending part. Each 
bar, towards the middle, is bent towards its fellow, like the larger first pair, and the two 
are twice united by a cross band. The front commissural band sends forwards a pair 
of three-rayed rods spreading out over the others and looking forwards ; and from its 
hind margin it gives off a single median rod, which passes directly backwards over the 
hinder commissure, and then breaks up into two larger sub-terminal and two smaller 
terminal rays. These four rays, and the points of both pairs of main pharyngo- 
branchials (p.br 1 ., p.br 2 .) end in the transverse crenate hind margin of the great 
upper pharyngeal “ velum ” (Plate 17, fig. 1, vl.). This structure is much like that 
seen in Myxine (Plate 15, fig. 6), but in that Fish the 2nd is free from the 1st pharyngo- 
branchial, and the median bar of the former is absent. 
The complexity of this reticulation of cartilage suggests the presence of a 3rd 
pharyngo-branchial rudiment, but I am not certain of its existence. 
The huge basal bar is quite like that of Myxine (Plate 16, figs. 1, 2, 6, b.hy., b.br 1 .), 
the front part, for more than a third of the whole length, being composed of hard 
cartilage, and the rest of vacuolar tissue ; this part is the 1st basi-branchial (b.br 1 .), 
and the other basi-hyal (b.hy.). This is a curious piece of special “ hypertrophy,” for 
the normally single basal bar is composed of two bars behind, and four in front, all 
large, solid bars, oval in section. The outer of the front pieces are the largest; a 
small fontanelle is seen where the six pieces meet, and they are all connected 
together by tracts of soft cartilage. Looking at the structure as a whole,—first, 
quadruple, then double, and then single, and composed of four varieties of connective 
tissue,—we see, at once, that it is merely an enormous development of the common 
“basi-visceral” element. It is hollow above, all along, as in Myxine; in front, to hold 
the secondary trough-shaped cartilage (supra-lingual), and behind, to receive the 
tendons of some of the muscles that work the whole lingual machinery. 
MDCCCLXXXIII. 3 F 
