AKI'-KISIIKS. 



17 



of t lie ( '\iirin(iiils, work in the mastication or dilani.-ition 

 of fiKHJ. The form of the carp-stone, as well as flu; t'orni, 

 iiuinhcr, and position of the teeth on the lower pha- 

 ryngeals, att'oril in most cases the most tennhlc charac- 

 ters for the definition of the Cyprinoid species and also, 

 to some extent, of the genera, and lunc heeti .iicnerally 

 emploved for this object ever since Agassiz" and IIkc- 

 KEI.' directed attention to this point. We shall often 

 return to these structures; here we need only remind 

 tiie reader that the said teeth on the lower ))haryn!ieals, 

 which latter nKi\- he more or less falciform or more 

 like hranchi;d :irehes'', are shed or renewed annually, 

 as .Ii'uiNi;' and (subse(piently) SiEHoi.i)' have jiointed 

 out. The upper pharyngeals are small, less remarkable, 

 and toothless. They He above the sides of the aforesaid 

 cushion in tlie jKisterior part of the roof of the |ili:irynx; 

 and in front of and outside them we hud, in most 

 cases, but with great irregularity, distinct or covered 

 (glandular) pseudobranchiu'. 



The short cesophagus is I'ecognisable internally by 

 the longitudinal folds of the mucous mend)i'ane. The 

 stomach is also short and shows very little, if any, 

 expansion. Its mucous membrane lies in zigzag folds 

 or is dowuA' like velvet. These fishes ha\e no dis- 

 tinct pN'loric part or jiyloric appendages, and the sto- 

 mach passes gradually into the intestine, the length of 

 wliicli 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 ;ind suli- 

 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- 

 K¥A. divideil the <\prinoids-' on this account into two 

 groups: Jfticnieiitri, with long intestine — represented 

 in the .Scandinavian fauna liy Ci/priniis and Carassius 

 — and Bmchi/cntri, among which we find all the rest 

 of our ("yprinoids. The gall-bladder lies on the right 



side (jf the stiim;irli and sends out a gall-duct into the 

 sMuie; the spleen lies abo\e or to the left of tlu; be- 

 ginning of the intestine. The hng'est oi'gan in the ab- 

 (himinnl ea\it\- under ordinary circumstances (when the 

 ovaries lire nut extraordinarily swollen) is the air- 

 i)l;\chler. This organ is extei'nally doul)](!, but intcinallx 

 continuous, consisting of an anterioi-, shorter ]iart and 

 a posterior, longer one, tapering lj<diin<l, which usualh- 

 follows the eur\'e of the uj)i)er wall of the abdominal 

 eavit\- iiaek to the very end of the cavity, and which 

 comniunicntes in IVnnt b\' means (jf the pneumatic duct 

 with the lesopliagus. The ovaries as well as the testes 

 are paired and closed, their discharging duets sharing 

 as usual with the urethrii- a eiimmon njierture just be- 

 hind the mouth of the rectum. Tlie kidneys lie along 

 the under surface of the s|iinMl column and are genendh' 

 most developed at the contracted part of the air-bladder. 



The most remarkable peculiarities of the skeleton 

 are the alterations which the first four abdominal ver- 

 tebra undergo in connexion with the development and 

 function of the so-called acoustic Itones. The bodies of 

 these vertebra? coalesce, as we have mentioned abov<!, 

 more or less firmly with each other, the boundaries 

 between them being usually marked, however, by distinct 

 sutures, even if the intervertebral cartilage has dis- 

 appeared. Thus, in the Ide for exahiple, all four are 

 divided from each other with almost eipial distinctness; 

 and the intervertebral cartilage is still present between 

 the bodies of at least the tliii'd and fourth vertebra', 

 the neural arches of \vhich, on the other hand, are more 

 firmly miited by a suture. In the Chub as well as in 

 the Bream the bodies of the second and third vertebrie 

 are almost perfectly confluent. In the Barbel the body 

 of the first vertebra is confluent with that of the se- 

 cond, and that of the third with 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 hoi'izontal direction and 

 originates from the body, also like the latter, without 

 perceptible suture. The third vertebra is apparently 



" Mem. Soc. Sc. Xat. Xftichafel, vol. 1 (1830), p. .06. 



' Abbildungeu und Beschreibungen der Fisclie Syrieiis nebs-t ciner iiencn ClassiKcntiou umi Knruklt-ristik siiiiimtlielier Gatlungcn der 

 Cyprineii, Stuttgart 1843 (reprinted from Russegger's Reisen, B. 1, Tli. 2). 



' Cf. above, p. 631, on the lower pharyngeals and teeth of the File-tishes. 



'' Mem. Soc. Pliys., d'Hist. Nat., Geneve, Tom. I (1821), p. 20. Bloch (^Fische JDeuUclihuci.i, Th. 1, p. 47) also suggested the 

 possibility of tliis. 



■■ ■S'lsswasserf. Mitletetir., p. 82. 



■^ Rtisseggers Reiseri, 1. c, p. 1001. 



