AGONUS DKCAIiONUS. 



207 



(JUS (■.•mills, wliicli ,-ii'c t'uniislicil with small, raised, 

 tiiliulai- iipcniiiizs, on flic tbreliead l)et\v('('ii the siipi'a- 

 ovbital spines and mi the ncciimt lielwccii the occipital 

 spines, respectively. The xciilral tins, which in tliciv 

 stnictiii'e — \\ith onl\- two soft ra\s and with thc^ spi- 

 nous ray hidden in thi' coniiexioii lictwecn it and the 

 outer soft ra\" — reinind us of certain species among the 

 Cntti, also give us a sexual distinction, as LCtkkx was 

 the first to point out, which likewise calls to mind the 

 Cotti. In the males the outer soft ray is considerably 

 elongated, measuring somewhat more than 11 % of the 

 length of the hodv or about half the distance from the 

 insertion of these tins to the beginning of the anal fin; 

 while in the females the length of the ventral tins is 

 much less, being only slightly more than, or ecpial to, 

 the longitudinal diameter of the eye. 



Afionns dccaf/ouiis attains a length of at least 21 

 cm. It is an arctic form, first discovered in Green- 

 land, and subsecjuently found by O. Torell in Bern 

 Fjord (Iceland) and by the Fiiniish explorers Nylander 

 and riADi) in Varanger Fjord (Norwegian Finmark). It 

 was found by the Norwegian Arctic Expedition of '76 — 

 78 at a considerable depth (between 123 and 260 

 fathoms) and in very cold watei- ( + 34"7 Fahr. to + 30'2 

 Fahr.), on clayey and stony bottoms, in the Arctic 

 Ocean i-ound Bear Island and Spitzbergen. The Swedish 



Expedition of 1868 found young specimens, 21 mm. in 

 length (ill all probability not more than a month old), 

 near the surl'ace, where the water was 3 or 4 fathoms 

 dee|), in l>iebde Bay, Spitzbergen, on the 29th of 

 August. One of these si)ecimens is here figured. 



In this s])ecies, as in the following one, the colour- 

 ing is distributed accoi'ding to the typical arrangement 

 in Cottiis. It is yellowish gray, with dark transverse 



Fig. (50. Young sviecimcii of Aijoiius decayonus, Liebde Bay (Spitz- 

 bergen), taken at the surface, 2iHh Aug., 1868. Malmgren and Smitt. 



bands, the situation of which is more minutely shown 

 in the figure (p. 205). 



Instead of giving a more detailed description we 

 may refer to the following tal)le, which gives the most 

 important relations of form in th(! two specimens of 

 the Royal ^luseum from Greenland, side by side with 

 which we have set the corresponding measurements in 

 three specimens of the following .species. We may here 

 trace the tendency of the changes of growth and the 

 consecjuent I'elative position of the two species, as well 

 as the respects in which constant specific characters 

 appear, to judge by the materials at our disposal. 



in % of the lensTth of the body 



I.eniflh 111' llic holly cxprcsseil in inilllinctres _ 



head ,,- - 



!..on!;itu(linul iliiiinetev of the ('\e _. --. ,, „ ,, ., ., •, :. •» 



nistauee hetween the tivst ilorsiil fin and the tip of the snout ., ., ., ., 



Distance between the insertion of the ventral tins and the beginning of the anal tin ., ,, ., ., ,, ., ., ., 



Least depth of the tail ., ., ., ., ,, „ ., 



Breadth of the body across the base of the pectoral tins „ „ ?, ., 



Depth ,, t tlie beginning of the first dorsal tin.. , ., „ „ „ ,, -, ., 



Least depth of tlie tail in 'i of the length of the head 



., ,, „ „ ,. ., „ „ .. longitudinal diameter of the eye 



., ., ., ,, ., ,. „ „ leasl breadth of the interorbital space 



., ,, „ ., ,, ,, „ „ .. length of the lower jaw 



.. ,. ,, ,, ,. „ ., distance between the first dorsal tin and the tip of the snout 



., ., ,, ., , ., ., height of the first dorsal hn - - 



., ., ,, „ ., second ., ., 



„ ,, „ ,, ,, .. ,. ., ., length of the base of the anal fin 



Distance between the insertion of the ventr.il tins mid the beginning of the anal fin in % of the distance be- 

 tween the anal fin and the lip of the snout 



Breadth of the body across the base of the pectoral fins in % of the length of the head 



Length of the ventral fins in % of the length of the pectoral fins 



„ , ., ., „ „ ,. distance between the insertion of llie ventral tins and the beginning of 



the anal fin 



Length of the head in ^ of the dislJince bettvcen the first dorsal fin and the lip of the snout 



