39 
on to the arches, the only connection between the arches 
and the rakers being that in older specimens and in some 
places the position of the raker is indicated on the arch by 
a faint elevation. Their number and position, however, 
was in the few specimens examined remarkably constant 
and symmetrical, so that the following formula may apply 
to either side of most individuals :— 
pou Tal IV. V 
see ee | Se sees Ee ee 
Hypo-branchial | 2 | 8 : 0 0 0 
Cerato-branchial .... 5 | 6 | 6 0 
i 0 0 0 
Epi-branchial .... 3 
Gill Rays.—The gill filaments are supported by series 
of very delicate fragile gill rays fused together by their 
bases like a comb, which it is hardly practicable to dissect, 
but which are quite obvious in sections of the gills. They 
radiate out from the branchial arches as usual, and occur 
in pairs—one to each demibranch of the arch. 
Kyeless Side. 
Branchial Arch I.—<A1] segments slightly shorter and 
not so robust, the hypo-branchial markedly so, nor is the 
latter so deeply socketed into basi-branchials I. and II. as 
on the ocular side. The pharyngo-branchial also articu- 
lates with the skull, but the depression in the skull with 
which it is connected is deeper and more marked. 
Branchial Arch II.—Practically no difference except 
that the basi-branchial articulation is stronger on the 
ocular side. 
Branchial Arch III.—The segments are of the same 
length, but are somewhat less robust. The ventral arch 
transmitting the ventral aorta has been already described. 
