986 
so retained in contact with the branchie con- 
tinually absorbing from the air a sufficiency of 
oxygen to carry on the respiratory process. 
An important group of Fishes (the “ Pha- 
ryngiens labyrinthiformes” of Cuv.) are cha- 
racterized by a very peculiar formation of the 
anterior superior pharyngeal bones, which 
enables them to live out of the water for a 
considerable length of time, so that many of 
them, as we are assured by authors, not un- 
frequently come on dry land, and even, as in 
the case of the Anabas scandens, or climbing 
Perch, mount into trees, a faculty for which 
they are indebted to the following remarkable 
conformation. 
Their inferior pharyngeals and the posterior 
of their superior pharyngeal bones present the 
usual arrangement and are studded with teeth, 
but the two anterior pharyngeals on each side 
are spread out into thin lamine folded upon 
themselves in divers ways, so as to form a light 
complicated mass, (which Cuvier* compares to 
a curly cabbage, or to certain forms of lami- 
nated eschars and millepores,) over which 
numerous vessels are distributed, but whether 
derived from the branchial artery or the aorta 
remains uncertain. In order to lodge these 
singular cellular organs the head is consider- 
ably dilated in breadth, and with the same 
intention the cranium is produced upwards by 
a vertical crest so as to increase the height of 
the lateral chambers in which the foliaceous 
masses are lodged. Externally, each of these 
chambers is partially covered by the bones of 
the cranium and by the opercular pieces ; and 
when the operculum is raised, a membrane is 
seen to be tightly expanded between it and the 
opercular bone so as to enclose the cavity, 
leaving only a small aperture of communica- 
tion with the exterior, which leads equally to 
the labyrinthiform apparatus and the branchial 
chamber. This bony labyrinth, therefore, so 
carefully enclosed on all sides, and which re- 
ceives water equally with the branchie when- 
ever the fish opens its mouth, will retain the 
water so taken in between its lamella where- 
with to moisten the branchiz for a considerable 
length of time, so that the fish may live for 
hours or perhaps even for days out of the 
water. 
The Lophobranchii form a remarkable group, 
distinguished from all other races of osseous 
Fishes by the peculiar structure of their bran- 
chial organs. In these, called from their pecu- 
liar shapes and external armour “ pipe-fishes,” 
(Syngnathus, Hippocampus, §c.) the vascular 
fringes appended to the branchial arches, in- 
stead of consisting of lamelle arranged in a 
pectinated form, are collected into tufts ar- 
ranged in a double series along the convexity 
of each branchial arch. The essential character 
of these tufts varies, however, in no respect 
from that of gills of the ordinary construction, 
and in like manner the water passes from the 
mouth through five apertures leading from the 
pharynx into the branchial chamber, whence, 
* Hist. des Poissons, tom. 8. 
PISCES. 
after bathing the tufted gills, it escapes through . 
a single small opercular fissure. : 
The Sturgeons ( Sturionide ), which in many 
points of their economy seem intermediate be- 
tween the osseous and cartilaginous Fishes, 
resemble the former in the disposition of their 
organs of respiration. The gills of the Stur- 
geon are constructed precisely in the same 
manner as in ordinary osseous Fishes, only 
differing in some respects as to form, the bran- 
chial arches being more bent and the vascular 
lamin united for a greater extent; the respired 
water, moreover, escapes in like manner through 
a single opercular slit. ’ 
In the Plagiostome cartilaginous Fishes 
(“ Chondropterygii & branchies fixés,” oa 
the mechanical arrangement of the i 
organs presents very important modifications, 
the water which passes from the mouth over 
the gills no longer escaping through an oper- 
cular opening, but being expelled through five 
distinct orifices situated on each side of the 
body. Inthe Sharks and Rays the condition of 
the breathing organs is essentially similar, so 
that the same description will apply to both. 
The four branchial arches in these Fishes are 
of a soft cartilaginous consistence, and instead 
of hanging free in the branchial chamber as 
they do in the osseous genera, stretch quite 
across that cavity to have their external a 
fixed to its outer walls, thus dividing it like so 
many bulk-heads into five distinct compart- 
ments, which have no communication with 
each other. A wide branchial fissure admits 
water from the pharynx into each of these com- 
partments, which after passing over the gills is 
expelled by as many orifices situated upon the 
exterior of the body, the external opie 
being situated upon the sides of the in 
the Squalide (fig. 506, 9,9,q), but in the Skates, 
in consequence of the lateral extension of the 
body, they are placed upon the ventral surface. 
The gills themselves are broad vascular mem- 
branes spread out over the opposite faces of each 
cartilaginous septum, so that every compartment — 
of the branchial chamber has its walls tapes- 
tried with a respiratory surface, and forms a 
kind of bag lined with innumerable blood- 
vessels, through which the water must int 
its course from the mouth to the ex Open-— 
ings upon the sides of the neck. 
The branchial membrane which thus covers 
the opposed walls that bound the respective” 
cavities into which the gi!l-chamber is divided, 
is entirely made up of numerous plicated, 
cular lamelle, each of which is gathered int 
close-set transverse folds sustaining the minute 
ramifications of the branchial vessels; and thesi 
again may be observed with a lens to be in like 
manner transversely plicated, thus presenting 
in the aggregate a surface of vast extent to thi 
influence ot the respiratory currents. In th 
anterior branchia the vascular layer is of cours 
affixed only to the posterior surface of the st 
porting membrane, the opposite side being st 
ported by cartilaginous rays.* : 
* Monro makes the following calculation rela- 
