36 



Medens saaledes den Række af disse Bentorne, der 

 løber langs Ryglinien, altid synes at strække sig uafbrudt 

 lige til Roden afCaudalen, og det saaledes ber er væsentlig 

 de enkelte Tuberklers Bygning, der varierer med flere eller 

 færre Tænder, med længere eller kortere Spidser. kan Si- 

 delinien undertiden være manglende i sin sidste Del, nden 

 at dette begrundes i Individets unge Alder. Medens 2 

 unge Hanner fra Stavangerfjorden i Norge (59°), optagne 

 fra 100 Favnes Dyb i 1872. have Sidelinien fuldt udviklet 

 lige til Haleroden med 35 — 37 Torne. skjønt Individernes 

 Totallængde ikke er over 38""".' er Sidelinien ufuldstændig 

 bos alle de 3 større, der erholdtes under Nordhavs-Expe- 

 ditionen ; hos det mindste standser den henimod Slutningen 

 af Analen, og har ialt 27 af disse benede Tuberkler; hos 

 de 2 ældre. der have 33 Tuberkler, standser den noget 

 bagenfor Analens Slutning. Det største Antal fandt Kroyer. 

 der angiver 41 — 42 for sine Typ-Exemplarer. og Malm. 

 som hos sin I. furciger, hvis Totallængde blot var 51""", 

 fandt 45. I hvilken Grad disse benede Tuberkler selv 

 variere i sin Bygning, har allerede Esmark gjort opmærk- 

 som paa i sine ovennævnte Bemau-kninger i det 10de Natur- 

 forsker-Mødes Forhandlinger. 



Intet af Nordhavs-Expeditionens 3 Individer havde 

 Spor af den Række benede Tuberkler langs Analen, som 

 ofte er tilstede hos Individer af Middelsstørrelse [ved ile 

 scandinaviske Kyster, ligesom denne ogsaa fandtes (ifølge 

 Dr. Liitken) hos det ene af Kroyers Typ-Exemplarer fra 

 Grønland. En lignende Række udviste et Exemplar fra 

 Spitsbergen, som jeg i 1879 havde Leilighed til at under- 

 søge i Riks-Musæet i Stockholm. Disse Individer repræ- 

 sentere Malms I. fwciger. 



At ligeledes den øvre gaffeldelte Torn paa Praeoper- 

 eulum kan være ganske eller næsten udelt (hvilket er Re- 

 gelen hos ganske unge Individer), har tidligere været gjort 

 opmærksom paa. Dette var saaledes Tilfældét paa den ene 

 Side af et af Nordhavs-Expeditionens større Individer. 



Straaleantallet findes ligeledes at variere ikke ubety- 

 deligt, hvad der fremgaar af nedenstaaende Fremstilling af 

 de forskjellige Forfatteres Angivelser. 



Grønland (Kr. 1844); Typ-Expl. 

 Spitsbergen 1861 (Malmgr. 1864). 

 Grønland (Malmgr. 1864). 

 Norge 1866— 72(flereExpl.G1874). 

 Norge 1866—72 (C. 1874). 

 (flere Expl. Liitken 1876). 

 Bohuslen 1861 (Malmgr. 1877).' 

 Spitsbergen 1868 (C). 

 Spitsbergen 1868 (C). 

 Spitsbergen 1872 (C). 

 Spitsbergen 1872 (C). 



The row of osseous spines along the mesial line in- 

 variably appearing to exend as a continuous series to the 

 origin of the caudal fin, and the exceptional character of 

 the armature in this region being chiefly displayed in the 

 structure of the individual tubercles, which vary in the 

 number of the teetli and the length of the points, the 

 terminal part of the lateral line is sometimes wanting 

 altogether, which cannot be accounted for by the immaturity 

 of the individual. Two young male examples from the Sta- 

 vanger Fjord, in Norway (in lat. 59° N.), taken at a depth 

 of 50(1 fathoms, in 1872. had the lateral line fully devel- 

 oped to the root of the tail, number of spines 35 — 37 ; 

 and yet the total length did not exceed 38 '"'". whereas in 

 all three of the larger specimens, obtained on the Expe- 

 dition, the lateral line is more or less imperfect; in the 

 smallest, furnished with 27 osseous spines, it breaks off a 

 short distance from the termination of the anal ; in the two 

 maturer examples it has 33 tubercles, and terminates a little 

 beyond the posterior extremity of the anal. The largest 

 number of tubercles yet observed is 41 — 42, in Kriiyer's 

 typical specimens, and 45 in Malm's l.fnrciger (total length 

 only 51"""). The extent to which the tubercles vary in 

 structure has been pointed out by Professor Esmark. in a 

 paper read before the 10th General Meeting of Naturalists. 



No one of the three specimens taken on the Expe- 

 dition exhibited traces of the series of osseous tubercles 

 along the anal tin frequently observed in half-grown 

 examples from the shores of Scandinavia, and which, ac- 

 cording to Dr. Liitken. occurs in one of Kroyer's typical 

 specimens from Greenland. An example from Spitzbergen 

 which I had the oppertunely of examiuing in 1879, in the 

 Riks Museum at Stockholm, was furnished with a similar 

 series. These individuals represent I. fitrcic/er. Malm. 



That the upper spine' on the preoperculum. com- 

 monly bifurcate, in some individuals occurs with little or 

 no appearance of .furcation, more particularly in the early 

 stage of growth, has been noticed before. This distinction 

 was observed in a specimen taken on the Expedition. 



The very considerable variation in the nnmber of the 

 fin-rays is apparent from the subjoined table, comparing 

 the formulae given by the different authors. 



Greenland (Kr. 1844); typ. spec. 

 Spitzbergen, 1861 (Malmgr. 1864). 

 Greenland (Malmgr. 1864). 

 Norw. 1 866— 72(sever. spec. C. 1874). 

 Norway 1866—72 (C. 1874). 

 (several specim. Liitken 1876). 

 Bohuslen 1861 (Malmgr. 1877). 

 Spitzbergen 1868 (C). 

 Spitzbergen 1868 (C). 

 Spitzbergen 1872 (C). 

 Spitzbergen 1872 (C). 



