CARP-FISHES. 
717 
of the Cyprinoids, work in the mastication or dilaniation 
of food. The form of the carp-stone, as well as the form, 
number, and position of the teeth on the lower pha- 
ryngeals, afford in most cases the most tenable charac- 
ters for the definition of the Cyprinoid species and also, 
to some extent, of the genera, and have been generally 
employed for this object ever since Agassiz" and Hec- 
kel* directed attention to this point. We shall often 
return to these structures; here we need only remind 
the reader that the said teeth on the lower pharyngeals, 
which latter may be more or less falciform or more 
like branchial arches 0 , are shed or renewed annually, 
as JuRiNE d and (subsequently) Siebold 0 have pointed 
out. The upper pharyngeals are small, less remarkable, 
and toothless. They lie above the sides of the aforesaid 
cushion in the posterior part of the roof of the pharynx; 
and in front of and outside them we find, in most 
cases, but with great irregularity, distinct or covered 
(glandular) pseudobranchia?. 
The short oesophagus is recognisable internally by 
the longitudinal folds of the mucous membrane. The 
stomach is also short and shows very little, if any, 
expansion. Its mucous membrane lies in zigzag folds 
or is downy like velvet. These fishes have no dis- 
tinct pyloric part or pyloric appendages, and the sto- 
mach passes gradually into the intestine, the length of 
which is exceedingly variable, for it sometimes forms 
only two coils, sometimes five, before it runs back 
to the vent. The intestine ends in a more or less 
defined rectum, which is marked by longitudinal folds 
of the mucous membrane. Often the whole digestive 
canal lies imbedded in a more or less lobate and sub- 
divided mass of liver and in a thick layer of fat. The 
variations in the length of the intestinal canal are con- 
nected with the diet: a greater proportion of animal 
food is accompanied by a shorter intestinal canal. Hec- 
kel divided the Cyprinoids 7 on this account into two 
groups: Macroentri , with long intestine — represented 
in the Scandinavian fauna by Cyprinus and Carassius 
— and BracJiyentri, among which we find all the rest 
of our Cyprinoids. The gall-bladder lies on the right 
side of the stomach and sends out a gall-duct into the 
same; the spleen lies above or to the left of the be- 
ginning of the intestine. The largest organ in the ab- 
dominal cavity under ordinary circumstances (when the 
ovaries are not extraordinarily swollen) is the air- 
bladder. This organ is externally double, but internally 
continuous, consisting of an anterior, shorter part and 
a posterior, longer one, tapering behind, which usually 
follows the curve of the upper Avail of the abdominal 
cavity back to the very end of the cavity, and Avhich 
communicates in front by means, of the pneumatic duct 
with the oesophagus. The ovaries as avcII as the testes 
are paired and closed, their discharging ducts sharing 
as usual Avitli the urethra a common aperture just be- 
hind the mouth of the rectum. The kidneys lie along 
the under surface of the spinal column and are generally 
most developed at the contracted part of the air-bladder. 
The most remarkable peculiarities of the skeleton 
are the alterations Avhich the first four abdominal ver- 
tebrae undergo in connexion Avitb the development and 
function of the so-called acoustic bones. The bodies of 
these vertebrae coalesce, as Ave have mentioned above, 
more or less firmly with each other, the boundaries 
between them being usually marked, hoAvever, by distinct 
sutures, even if the intervertebral cartilage has dis- 
appeared. Thus, in the Tde for example, all four are 
divided from each other Avith almost equal distinctness; 
and the intervertebral cartilage' is still present between 
the bodies of at least the third and fourth vertebra?, 
the neural arches of Avhich, on the other hand, are more 
firmly united by a suture. In the Chub as Avell as in 
the Bream the bodies of the second and third vertebrae 
are almost perfectly confluent. In the Barbel the body 
of the first vertebra is confluent Avith that of the se- 
cond, and that of the third Avith that of the fourth. 
The body of the first vertebra is always the small- 
est. Its transverse process, which is also considerably 
smaller than that of the second vertebra, stands, like 
the latter, straight out in a horizontal direction and 
originates from the body, also like the latter, Avithout 
perceptible suture. The third vertebra is apparently 
° Mem. Soc. Sc. Nat. Neuchatel, vo], 1 (1836), p. 36. 
b Abbildungen und Beschreibungen der Fisclie Syriens nebst einer neuen Classification irac] Karakteristik sammtlicher Gattungen der 
Cypfinen, Stuttgart 1843 (reprinted from Russegger’s Reisen, B. 1, Tli. 2). 
c Cf. above, p. 631, on the lower pharyngeals and teeth of the File-fishes. 
d Mem. Soc. Phys., d’Hist. Nat., Geneve. Tom. I (1821), p. 20. Bloch ( Fisclie Deutschland s, Th. 1, p. 47) also suggested the 
possibility of this. 
e Siisswasserf. Mitteleur ., p. 82. 
1 Russeggers Reisen , 1. c., p. 1001. 
