41 



Sidelinien dannes ai en sammenhængende Rekke tan- 

 dede Benplader, hvis Antal, der svarer til Hvirvelantallet, 

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

 hele Løb noget ovenfor Legemets Midtlinie. gjør en ube- 

 tydelig Sænkning ned onder Iste Dorsal, men hæver sig 

 atter, og lolier heretter Hge ud mod Caudalen. Fra Unger 

 af ln his hamatus. hvor de 1'dvoxedes Charactercr endnu ikke 

 ere fuldt udviklede, kunne ligestore Unger af Triglops 

 kjendes ved Sideliniens Løb, idet denne hos Indus danner 

 en opad convex, hos Trighps en opad concav Bue onder 

 Iste Dorsal. 



Ovenfor Sidelinien strækker sig en Række Bentorne 

 langs hele Granden af Dorsalerne, der taber sig omtrent 

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

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

 de tildels ere lidet fremtrædende af Hudens chagrinerede 

 Parti. 



De skraatlohende Hudfolder danne oprindelig jFort- 

 sattelser af Sideliniens Benplader, og bedække fulclkommen 

 Legemets Sider nedenfor denne. Ikke altid ibrtsætter den 

 samme Hudfold sig uden Afbrydelse lige ned til Ventral- 

 lmien. men nve af forskjellig Længde begynde og ophore 

 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 bekhedt. 



Det Tidspunkt, da disse characteristiske Tverstriber, 

 samt Tornerækkerne udvikle sig hos Ungerne, synes at være 

 noget varierende. Sandsynligvis blive Hannerne tidligere 

 væbnede, end Hunnerne. Saaledes har jeg undersøgt Un- 

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

 Totallængde har været mellem 26 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 18(34). 

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

 til at undersoge. endnu glat overalt ; Sidelinien var her synlig 

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

 secle for Slutningen af 2den Dorsal, men intet Spor viste 

 sig af Tverstriberne ; den øvre Tornenekke var ligeledes 

 blot antydet ved bløde Papiller, der endnu knapt vare 

 ossiiicerede eller væbnede. Dette sidste Individ var sand- 

 synligvis en Hun. 



Finnerne. De 2 Dorsaler ere adskilte ved et Mel- 

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

 Diameter. Alle Straaler ere spinkle og skjore som Glas. 

 saaledes at Finnerne ofte ere mere eller mindre defecte. 

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

 2den' Dorsal har 23 til -2(5 Straaler. Analen. der har den 

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

 samme Straaleantal. som denne sidste Finne; hegge 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. 

 har, foruden paa hver Side et Antal korte Støttestraaler. 



Deu norske Nordlftiysexpedition. 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 vertebrae; it extends, 

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

 hending slightly downwards onder the first dorsal, from 

 whence, after regaining its original position, it passes straight 

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

 have not as yet the adult characters fully developed, may 

 he readily distinguished from young examples of 'fi/i/liips 

 by the upward sweep of the lateral line under the first 

 dorsal, which in Icelus is convex, in Trit/lopx 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 granulous 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 uninterruptedly to the ventral 

 line, others commencing and breaking pff almost everywhere, 

 and hence the total number of folds greatly exceeds that 

 of the osseous plates on the lateral line. Each of these 

 membranous folds is dentate, or rather serrate along its 

 posterior margin: they extend to the caudal tin; 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 develop would appear 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 yet 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 

 papillæ. 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 tin. 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 



6 ' 



