!16 



SCANDINAVIAN FISHES. 



In (be last four cohunns the rise or fall of the minibers is 

 foniiDOn to both species, and we can Hnd no consistent difference in 

 any of tlji- tliree proportions given. Still, it is only in the juvenile 

 stages of the latter species that we can find the same proportions as 

 in the former. This statement applies, however, only to the averages: 

 it is only in tlje character first given (the depth of the body) that 

 the difference is so marked that the character, to the best of our 

 knowledge at present, is independent of the individual variations. 

 We also see that the direction of development in this case is not 

 tlie same, for tlie proportion rises with age in the one form and sinks 

 in the other, assuming that the rule which holds good in this table 

 for Trachypterus arcticua, also applies to the earlier stages of this 

 species, which are still unknown. 



The Dcalfish attain.s a length of at least 2' ., nietre.s". 

 The ribbon-shaped body'' is of fairly uniform depth for 

 the greater part of its length Ijehind the head, but is 

 deepest at about the middle of this part'', whieh ends 

 at a varying distance behind the ^•ent. From this point 

 the outlines of the body sharply converge, at nboiit equal 

 angles upwards nnd downwards, towards tlie shallow 

 base of the caudal tin''. The liack behind the head is 

 almost entirely occupied by the continuous dorsal tin'', 

 the height' of which fairly closely follows the lines of 

 the body, with the exception of the fact that in front 

 it is lower, but steeper, and behind higher than the 

 latter. In front of this fin there probably lies in all 



young specimens a higher occipital or anterior dorsal 

 tin, whose 6 (sometimes only 5) rays are, however, fra- 

 gile, and generally disappear with age externally, though 

 their stumps may generally be traced in the dorsal 

 edge. Behind the dorsal tin rises the caudal tin de- 

 scribed above", sometimes in a vertical direction, but 

 sometimes leaning sharply backwards. (3f the stunted 

 ra^-s of the caudal tin (the original lowei' part thereof) 

 the stumps may generally be traced without difficulty, 

 three above and two below the end of the lateral line, as 

 well as the double spine (.spinous plate) which is situated 

 in fi-ont of them, on the under surface of the end of 

 the tail, with one point directed forwards and the other 

 backwards, and which has replaced the original lowest 

 (rudimentar) ") ray of the caudal tin. The singular ap- 

 pearance of the tish is further enhanced by the entire 

 absence of the anal tin and, usually, of the ventral fins, 

 though the latter, at least in specimens not more than 

 a metre in length, generally leave traces behind them'' 

 in the form of a ro^v of stumps (from five or less to 

 ten) on each side of tlie ventral margin, just behind 

 the perpendicular from the end of the horizontal base 

 of the pectoral tin. The pectoral fins are turned up- 



" The largest specimen from Norway examined by Collett was 246 cm, long. The occurrence alleged by fishermen of specimens 

 3 m, in length has not been confirmed up to the present. 



'' The body, it is stated, becomes consideral)ly thinner after death ami on dry land. In the specimens preserved in spirits it is 

 thickest at the head, across the upper articulation of tlie preoperculmn, where the breadth measures 3 or 4 'Jo of the length. 



' Even in specimens from 830 to 98.5 mm, in length, according to Lutkex, the greatest depth of the body may be no more than 

 15 or It) °o of the length; but it afterwards rises to at least 20 \ thereof — according to Siwrre-Schneider, 21'4 °o. The greatest depth 

 usually occurs in front of the vent, but in a specimen about 11 dm, long, from West Fjord (Norway) the body is deepest just at the vent. 



''■ The least depth of the tail measures only from about 1 to 2V2 % of the length of the body (the latter measurement according to 

 Reinhakdt). Still, it is so strongly compressed that at this point the thickness (breadth) of the body is only about '/j of the depth, 



" Tlie roughness of the rays of the dorsal fin, caused by small spines along their sides, is extremely inconstant. Sometimes, especially 

 in old specimens, all the rays are smooth to the touch, if we except the basal spine on each side. 



■' The length of the longest ray of the dorsal fin, about the 100th from the beginning, is about lialf the greatest depth of the body. 



•'' In specimens between 830 and 1,505 mm, long the length of the caudal fin varies, according to LUtken, between 18 and 11 '/o % 

 of that of the body; in a specimen 1,870 mm. long he found tlie length of the caudal fin to be only 9", % of that of the body. 



'' In a specimen 7G cm. long Sparre-Schneider found the stump of the first ray of the ventral fin to measure 43 mm. in length. 



