41 



Sidelinien dannes af en sammenhængende Række tan- 

 dede Benplader. hvis Antal. der svarer til HvirvelantaUet, 

 er 47 — 49. eller undertiden et Par færre; den ligger i sit 

 hele Løb noget ovenfor Legemets Midtlinie, gjør en ube- 

 tydelig Sænkning ned under Iste Dorsal, men hæver sig 

 atter, og løber herefter lige ud mod Caudalen. Fra Unger 

 af Icélus hamatus, hvor de Udvoxedes Characterer endnu ikke 

 ere fuldt udviklede. kunne ligestore Unger af Trighps 

 kjendes ved Sideliuiens Løb, idet denne \\os" Irelus danner 

 en opad convex, hos TrigJops en opad concav Bue under 

 Iste Dorsal. 



Ovenfor Sidelinien strækker sig en Række Bentorne 

 langs hele (xrunden af Dorsalerne. der taber sig omtrent 

 ved Midten af 2den Dorsal. Hos de yngre Individer ere 

 disse Bentorne højere og skarpere, end. hos de ældre. hvor 

 de tildels ere lidet fremtrædende af Hudens chagi'inerede 

 Parti. 



De skraatløbende Hudfolder danne opriudelig jFort- 

 sættelser af Sideliniens Benplader, og bedække fuldkommen 

 Legemets Sider nedenfor denne. Ikke altid fortsætter den 

 samme Hudfold. sig uden Afbrydelse lige ned til Ventral- 

 linien. men nye af forskjellig Længde begynde og ophøre 

 næsten overalt, saaledes at deres Antal nedad bliver langt 

 større, end Benpladernes i Sidelinien. Enhver af disse 

 Hudfolde er i sin bagre Rand tint tandet; de gaa lige ud 

 til Caudalen, og med lignende Hudfolder er ligeledes Stru- 

 ben beklædt. 



Det Tidspunkt, da disse characteristiske Tverstriber, 

 samt Tornerækkerne udvikle sig hos Ungerne, synes at være 

 noget varierende. Saudsynligvis blive Hannerne tidligere 

 væbnede, end Hunnerne. vSaaledes har jeg undersøgt Un- 

 ger (fra Norge), der sandsynligvis have været Hanner, hvis 

 Totallæugde har va'ret melleiu :^6 og 30""", og som allerede 

 havde saavel Tverstriberne. som Tornerækkerne antydede 

 eller i Frembrud; derimod var et andet Individ fra Spits, 

 bergen (erholdt under den svenske Expedition i 1864), 

 hvis Totall. var 37'""', og som jeg i 1879 havde Lejlighed 

 til at undersøge, endnu glat overalt ; Sidelinien var her synlig 

 som en Række hvidagtige. parvis stillede Papiller, der stand- 

 sede før Slutningen af 2den Dorsal, men intet Spor viste 

 sig af Tverstriberne; den øvre Tornerække var ligeledes 

 blot antydet ved bløde Papiller, der endnu knapt vare 

 ossificerede eller væbnede. Dette sidste Individ var sand- 

 synligvis en Hun. 



Finnerne. De 2 Dorsaler ere adskilte ved et Mel- 

 lemruni. der dog ikke plejer at være større, end Lindsens 

 Diameter. Alle Straaler ere spinkle og skjøre som Glas 

 saaledes at Finnerne ofte ere mere eller mindre defecte. 

 Iste Dorsal er højere. end 2den. og har 10 til 13 Straaler ; 

 2den Dorsal har 23 til 26 Straaler. Aualen, der har den 

 samme Længde og Bygning, som 2den Dorsal, har det 

 samme Straaleantal, som denne sidste Finne; begge disse 

 slutte i betydelig Afstand fra Caudalen. Pectoralernes 

 Straaleantal ligger mellem 17 og 21. Caudalen, der næsten 

 er ret afskaaret i sin bagre Rand, eller svagt emargineret, 

 bar, foruden paa hver Side et Antal korte Støttestraaler, 



Deu norske Nordliavsexpeditinn. Collett : Fiske. 



The lateral line consists of a continuous series of 

 dentate osseous plates, corresponding in number (47 — 49. 

 sometimes one or two fewer) with the vertebræ ; it extends, 

 throughout its entire length, a little above the mesial line, 

 bending slightly downwards under the first dorsal, from 

 whence, after regaining its original position, it passes straight 

 to the caudal fin. Young individuals of Icelus hamatus, which 

 have not as yet the adult characters fully developed, may 

 be readily distinguished from young examples of Triglojjs 

 by the upward sweep of the lateral line under the first 

 dorsal, which in Iceliis is convex, in TrigJops concave. 



Above the lateral line is a series of osseous spines, 

 extending along the base of both dorsals; about the 

 middle of the second it ceases however to be obvious. In 

 young examples these spines are longer and sharper than 

 in adults, which have them in some cases but very sligtly 

 elevated above the grauulous surface of the skin. 



The oblique membranous folds are at first continua- 

 tions of the osseous plates of the lateral line, covering the 

 whole of both sides of the body beneath it. The same 

 fold does not always extend uninterruptedlj- to the ventral 

 line, others commencing and breaking off almost everywhere, 

 and hence the total number of folds greatly exceeds that 

 of the osseous plates ou the lateral line. Eacli of these 

 membranous folds is dentate, or rather serrate along its 

 2)osterior margin; they extend to the caudal fin; similar 

 transverse folds cover the throat. 



The exact stage of growth at which these character- 

 istic transverse stripes and series of osseous spines begin 

 to develoji would apjDear to vary. Probably males acquire 

 armature earlier than females. I have examined young 

 individuals (from Norway), most likely males, having a to- 

 tal length of between 26 and 30"'", in which both the 

 transverse stripes and the series ,of spines were either 

 rudimentary or in course of development, whereas an 

 example from the coast of Spitzbergen (taken on the 

 Swedish Expedition in 1864), total length 37™"'. which I 

 had an opportunity of examining in 1879. was as yét per- 

 fectly smooth. In that specimen, the lateral line was 

 obvious as a row of whitish papillæ, terminating near 

 the extremity of the 2nd dorsal; but of transverse stripes 

 no vestige was perceptible ; also the upper row of spines in 

 the rudimentary stage was marked out with soft and tumid 

 papilhe. which as yet exhibited little or no trace of arming. 

 This individual was probably a female. 



Fins. — The two dorsals separate; space between 

 them generally not greater than the diameter of the lens; 

 all the rays slender, and brittle as glass; hence the fins 

 themselves, in the great majority of examples, are in a 

 more or less mutilated condition. Height of first dorsal 

 exceeds that of second; number of rays in former 10 — -13. 

 in latter 23 — 26. The anal fin. length and structure cor- 

 responding to that of second dorsal, also furnished with 

 23 — 26 rays; both these fins placed at a considerable di- 

 stance from caudal; number of rays in pectorals varying 

 from 17 to 21. Posterior margin .of caudal square, fur- 

 nished on either side with a number of short auxiliary 







