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tory of the capillary system. The carrier of the purer blood 
is seen to occupy a deeper and, presumably, a safer position than 
does its fellow, at the bottom of the groove which is channelled 
out along the convex edge of its bony support. 
The arrows indicate the course of the blood. 
Fig. 6. Head of a species of Pipe-fish ( Syngncithus JEquoreus) from a pre- 
paration (No. 1041) in the Museum of the Royal College of 
Surgeons. 
The operculum on the right side has been removed, in order to 
display the gills, which are “composed of a double series of tufts 
on each of the four arches.” 
b a Bulbus arteriosus — the root, so to speak, of the trunk 
which gives off an arterial branch for the gills of either side. 
Fig. 7. Head of another specimen of the Pipe-fish ( Syngnathus Sp : ?) cap- 
tured by the author in an oyster-dredge off Seaview, Isle of 
Wight. 
o p Operculum, left side. Above and behind it is seen the 
small outlet (*), just large enough to admit a bristle, for the 
water which has bathed the gill-tufts. 
Fig. 8. The pharynx of the same specimen opened out in order to show the 
five fissures on either side which admit water to the tufted 
gills. 
Fig. 9. Much reduced from a sketch of a preparation (No. 1060) in the 
Museum of the Royal College of Surgeons, of the head of the 
Gray Shark ( Galeus communis). The right half of the head, 
through which a vertical longitudinal section has been made, is 
preserved in the preparation. In the pharynx five openings are 
seen, which, guarded by tooth-like projections, not bony as in 
osseous fishes, but more or less cartilaginous, allow of the influx 
of water, which, after bathing the gills paired in their chambers, 
finds exit by five fissures at the side of the head. 
cb oesophagus, or gullet. 
s p opening leading to the canal which terminates externally 
at the so-called “ spiracle ” (Spritzloch”).* 
The arrows indicate the direction of the water swallowed for 
respiration. 
Fig. 10 is a diagram (Schema) after Gegenbaur ( Grundzuge der Ver- 
gleichenden Anatomic, 2nd edit. fig. 210) of the cartilaginous skull 
and “ visceral” skeleton of one of the Sclachii, e.g. Sharks and 
Rays. 
o orbit, for lodgment of the eye. 
i. ii. First and second visceral arches, the former of which 
forms the boundary of the mouth, while the latter (“ hyoid ”) 
carries the tongue. 
hi. — viii. Branchial arches, comprising the rest of the visceral 
skeleton. 
* The remnant of the first “ visceral cleft,” which in the bony fishes be- 
comes closed up, but in ourselves is partly persistent as the external canal of 
the ear, and the Eustachian tube. 
