IIKRUINCi-FlsllKS. 



951 



Icaf-shnped extoiisioii of tlie jio.stcrior |i;irt of the supra- 

 cliivick' (scl). OH wliich too tlie posttuinporal canal oF 

 the lateral line is sometimes coiiliniied. In the ajipa- 

 ratus of the pcrtor,-il (ins \\c lind a peenliarity other- 

 wise unknown amonu' the Teleosts, hut eharaeteristie of 

 the (ianoids, nauieU' the outer row (lire) of hraehials 

 (basal hones of the peetoi'al tins) possessed by the 

 Herring". 



The organs of respiration are exceedingly well de- 

 veloped in the Cliipeoids: and they are protected as a 

 ride hv numerous am! long gill-i-akers. The pseudo- 

 hranehia' are large, and in many forms'' we iind t)n each 

 side a separate, a.ccess(n'y l>ranehial t-a\ity, resting on 

 the hindmost (fourth) epibranchial bone, \vhit:h is flat- 

 tened out into a plate for that purpose''. 



The digestive organs are as a ride eomparativeh- 

 simple, as in the Salmons. In all tiie Scandinavian 

 Herrings the short a-sophagus passes without external 

 distinction into the stomaeli, which is iirolonged into a 

 sac and pointed behind; and from the anterior part of 

 this sac issues in a forward direction the more or less 

 muscular pvloric portion, bending back quite as sharply 

 to pass into the intestine, which is fairly straight and 

 runs without any convolutions to the \ent. In exotic 

 forms however — as for example in the Brazilian CIk- 

 pea aiiclioria — the wall of tlie p\ loric portion is some- 

 times thickened, in the same way as in the Mugiloids 

 (see above, p. 329), into a sort of ingluvies, and the 

 prolongated intestine forms several convolutions. Other 

 Clupeoid forms show no backward prolongation of the 

 stomach. The pyloric appendages are generally well de- 

 veloped, liut quite as variable as in the Salmonoids. 

 Even among the Scandinavian species the variations in 

 the number of ca-cal apjiendages behind (below) the 

 pjdorus are very great, the Spi-at for example having 

 (i — 13, the common Herring 20 — 24, and the Shads 

 ahout 80. In some exotic Clupeoids'' the anterior por- 

 tion of the intestine (the duodenum), into wliicli the 

 pyloric appendages open, is so greatly prolonged that 

 bunches of these appendages occur almost throughout 

 the length of the abdominal cavity. The mucous mem- 

 brane lies, as usual, in longitudinal folds within the 

 oesophagus and stomach; but in the intestine the folds, 



which are most dexclopi'd, among the Seandina\ ian Clii- 

 |)euids, in the Shads, are transverse. The li\er is gene- 

 rally sniall, sometimes exceedingly small; the spleen 

 commonly long and narrow. The saccate organs of 

 reproduction with their complete excretorj' ducts are 

 so large during the time of propagation that tliey till 

 the greater pai't of the abdominal ca\ity; but at (jther 

 times, as in the generality of fishes, tlie\' are contracted, 

 sometimes scarcely visible. The connexions of the air- 

 l)ladder we have already mentioned, and w-e w-ill sini])ly 

 add that the pneumatic duct sometimes opens into the 

 posterior end of the stomach, sometimes further forward 

 or into the (esophagus. In some cases too the wall 

 of the air-blaflder lies so close to the dorsal side of 

 the stomach that the said duct is merely a very short 

 funnel. 



The scales are generally thin, deciduous, and cy- 

 cloid, smooth-margined, or, not unfrequently, notched or 

 e\en fringed with sharp s|>ines at the hind margin. The 

 head is always scaleless, as ^vell as the fins in general; 

 but the scales extend rather often over a great ])art of 

 the caudal fin and the base of the dorsal, more rarel)' 

 over that of the anal, and the axillary' scales of the 

 ]jectoral and venti'al tins are in most cases well develojied. 

 Es])ecially characteristic of most Herring forms are tiie 

 angular, spiuigerous scales at the abdominal margin, 

 which send out lateral processes to meet the lower ends 

 of most of the ribs (tig. 236, dh\ fig. 240, p. 958). 



The system of the lateral line shows great deve- 

 lopment, accompanied by a wide extension of the so- 

 called adipose membrane, on the head; liut the lateral 

 line proper is wanting on the sides of the body, wuth 

 the exception that in the common Herring we some- 

 times find the first (3 — 5) scales in one of the rows 

 pierced in the ordinary manner. In certain forms, as 

 for instance the Shads, the lateral line again crops up in 

 some scales of singular shape, situated on the caudal fin'. 



Tlie fins of the Clupeoids disjday the same wealth 

 of variations as those of the Carp-fishes, and here too 

 the variations principally affect the vertical (unpaired) 

 fins. The dorsal, -which is never very long, sometimes 

 Slitters reduction to the vanishing ])oint; the anal, on 

 the other hand, is sometimes exceedinulv long, occa- 



" Cf. Davidoff ou tlie vt'ntral fins of tlie Cypriuoiils; see above [j. 7 IS. Tliesc bones appear in a earcilaginoiis form in several otlier Pliysosloins. 

 ' See Hyrtl, Cber die accessorischeu Kiemenonjane der Chipcaceen, DeuUscbr. Akad. Wiss. Wicn. Malb. Xatiirw. Classe, Bd X 

 (1885), p. 47. 



' This spreading of the bone ma_v be seen in the coiiimou Herring, though the accessory branchial cavity is not present. 

 '' See Hyktl, 1. c, p. 51. 



' See Heckel und Kner, Sidisicctsserri.iclie dri- Oftreicliischeii ^fon(ln■hil•, pp. 230, 2.31. 

 Scandinavian Fisliti. 120 



