810 



SCAXDIXAVIAN FISHKS. 



iiiil)ricatfcl, iiiid a greater ]iart of tlieir surface is tliiis 

 left bare, the rule being that in this h\brid most of 

 the scales, at least those on the middle of the sides of 

 tlie body, have the free (hind), cxternalh- \isilile [)or- 

 tion lialf (or more) as long as deep, while in tiie pre- 

 ceding hybrid, as in th(! Rudd and the White Bream, 

 the length of tiie said part of t'ach scale is less than 

 half its deptli. Tlie same difference in the position 

 of the dorsal tin as appeal's l)et\\een the Roach on one 

 hand, the Rudd and ^\'hite J>ream on the other, is 

 also maintained hen;, the distance between the tip of 

 the snout and tlie Ijeginning of the said tin being less 

 in tliis hyln-id than lialf the length of the bod-\-. In 

 the specimen examined, it is true, the dorsal tin con- 

 tains 9 branched rays; l)ut the last of them is slender 

 and branched oidv at the tij), not, as is generally the 

 case in the Cyprinoids, divided almost to the base. 

 The pharyngeal teeth we liave not been able to exa- 

 mine; the above remark on tliis iiead is taken from 

 .Tackkl, wlio found tliem to number: 0(1 or 2), 6(5) 

 —5(6), Ud or -2). 



Tliis form, aceording to Mr. Svexs.son, is the most 

 common hy]>rid in the River Helge and the lakes 

 thi'ough whicii this river tlows as it approaches the 

 sea. Kristianstad Museum p(jssesses three stuffed spe- 

 cimens, one of which we liave been enabled to examine 

 by the kindness of Lecturer \\'AnLSTEDT. It is a male, 

 caught on the 4th of May, 1S72, with the small, ver- 

 rucose tubercles characteristic of the spawning season, 

 on the sides of the head (thickest on tiie gill-covers), 

 the lateral scales on the forepart of the body, and the 

 inner surface of the pectoral tins. The coloration seems 

 to iiave lieeii that typical of the Roach, tlie front part 

 of tile anal tin, iio\\ever, being of the lilack colour 

 frequenth" present in the White Bream. The entire 

 length to the tip of the lower caudal lobe is 29 cm., 

 but to the end of the middle caudal rays — the measure- 

 ment constantly tei'iued in tliis work, unless otiier- 

 Mise specitied, the length of the body — only 256 mm. 

 The greatest depth is .3(l'7 ^, and the least depth 10 %, 

 of the length of the b<Kly. The greatest thickness — 

 in the stuffed specimen just in front of the dorsal tin 



— measures .37'6 % of the greatest depth. The length 

 of the head is 2U"7 % of that of the body, and the 

 postorbital length of tlie same part half the entire 

 length of the same. The distance from the tip of the 

 snuut t(i tiie beginning of the dorsal tin is sliglitly less 

 than half the length of the bodj'. The base of the 

 dorsal tin measures 12'5 %, its longest rav 20'.3 %, of 

 the length of the body, and its last rav rather more 

 than ''3 (34\2 %) of the length of the longest ray. 

 The beginning of the anal fin lies at a distance from 

 the tip of the snout equal to 65'6 % of the length of 

 the body; its base measures 1()'S %, its longest ray 

 15 ?6, of the same length. The lengtli of the pectoral 

 tins is 16 % of that of the liody. Tlie ventral tins 

 are only slightly shoi'ter tlian the pectoral, and the 

 distance between them and the tip of the snout is 93 

 % of that l)et\veen the dorsal tin and the same point. 

 The length of the middle caudal rays occupies 9 ^ of 

 that of the body. Apart from all the other resem- 

 blances to the Roach, the jiosition of the ventral tins 

 in relation to the beginning of the dorsal tin shows 

 that one (jf the parent species of this hybrid must have 

 been the Roach; while the length of the pectoral tins 

 and the number of the scales admit of the assumption 

 that the White Bream was the other parent species, 

 but exclude the Bream from tlie possible progeiiitoi's 

 of this hybrid. 



Friiiii the same locality the Museum <if Kristian- 

 stad has I'eceived two other hylirids, similar to each 

 other, one of which is mentioned by Qvenxerstedt 

 (1. c.) under the head of "Ex. 2". The other (tig. 202) 

 was caught on the 17th of March, 1869, and has been 

 lent to me for the purpose of examination In' Mr. Wahl- 

 STEDT. It has the coloration of the ^^'llite Bream, in 

 particular tiie aliove-mentioned lilack spots" on the 

 sides of the bod}', the dorsal, anal, and caudal fins, and 

 the right ventral tin. Two similar spots of somewhat 

 larger size, with the same s\iiiptoms of skin-disease, 

 are situated on the right side of the head, the lower 

 on the hind margin of the preoperculum, the upper 

 on the front margin of the operculum. Tlie s])e(inien 

 evidentl}' has more White Bi'eam blood in it, a cir- 



" Tliese spots, wliicli are reiirodnced in our figure, cannot be minutely examined in a dried specimen, but are probably caused by 

 Holoatomnm cnticola (Nordmann, Mikrographische Beitruge zur Naturgescldchte der uirbMosen Tliiere. Heft. I, p. 40, taf. IV. fis. 1 — 4), a 

 Hatworni occurring in the skin and eyes of many fishes, and belonging to the Trematod order — cf. ftir exnmple tij;. 211, ji. 20!) in Max 

 VON DEM Borne, Handhiuli der Fisduuclit unci Fischerei. The spots themselves are pure black; and llie scales over wliich they extend are 

 partially abraded. At the centre of some spots is a blister, concealing a cavity which was ]irobably inhabited by tlie parasitic worm. 



