LYCODIN^. 



35 



number 23. Again, the pectoral fins in Z. endtpleurostictits are remarkable in that the lower rays are 

 somewhat prolonged and project distinct!}- forward beyond the middle ra>s; the posterior border 

 of the fin thus displays a distinct indentation. Collett even has remarked upon this peculiarity 

 in his }oung specimens of iL.esntarkii\ but he imagines that the fin changes during development — 

 a condition, Collett admits however, he has never seen, nor anything similar, in other species. We 

 have just seen (p. 29 and p. 31) that the real \oinig stage of L.esmarkii shows no such incision of the 

 pectoral — so that this may be considered as one of the characteristic features of L. eiidzplettrosii'ctits^). 



Again, the vertical fins have distincth' fewer fin-rays. In the L. esmarkii from Finmark, 

 according to Collett, the dorsal fin has 113— 118 ra)'s, the anal 97 — 102; in the specimens from the 

 Norw. North-Atlantic Expedition on the other hand, the dorsal fin has onh" 102 — 103 rays (from the 

 Ingolf Expedition, loo), and anal fin 88—92 rays (from the Ingolf Expedition, 90). Collett explains the 

 larger number of fin-rays in the large specimens from Finmark by assuming that vertebrse might 

 continue to be laid down along with the rays belonging to them during the wliole develojjment, but 

 I hardly think that Prof. Collett retains this opinion. 



Scales. Concerning the two largest specimens (265 and 295 mm.) from the Norw. Xorth-Atlan tic 

 Expedition, Collett has declared that the scaly covering extends forward in front of the beginning 

 of the dorsal fin, and on the belly to the veutrals; the dorsal and anal fins are likewise covered with 

 scales nearly to their margins. The 260 mm. long specimen from the Ingolf Expedition is quite similar. 

 In the two \oung specimens from the Norwegian North-Atlantic Expedition the scaled integument 

 is for the most part fulh' developed on the body; in the largest individual (114 mm. total length) 

 both the fins and the skin along their base are still naked ; in the smallest (81 mm. total length) the 

 scales on the tail are just beginning to develop*. With regard to the three larger specimens (165 — • 

 320 mm) in the Stockholm Museum, I have noted that the scales reach forward to the head and out 

 on to the unpaired fins; the 68 mm. long individual was still naked on the posterior half of the tail, 

 whereas the remaining part of the tail as well as the trunk to a little behind the base of the pectoral 

 shows indications of scales. 



The lateral line in I.. eudipleiirostictHS is very distinctly double (I have founded the name 

 of the species on this characteristic). It arises singly at the upper end of the gill-openings, forms a 

 slight arch over the free edge of the gill-cover, then divides a little posterior to this into two branches, 

 the upper of which, the mediolateral, is the most distinct and courses along the middle line of the 

 whole bod\- right to the caudal fin; the lower branch, the ventral, courses slantwise downwards towards 

 the anal fin, then runs along the edge of this fin towards the caudal fin. Such is the case in the 

 medium-sized and largest specimens. In the 81 mm. long specimen both lines are still indistinct, but 

 they are already apparent in the one 114 mm. long. — In L. esmarkii the mediolateral line is often 

 more or less indistinct. 



The colouration ol L. eudzpleiirostictus is rather different from that of the foregoing species 

 and can hardly be thought to give rise to that in L. esmarkii, as Collett believed. The ground- 



I) Smitt (I.e. 1901) states that the pectoral is incised in more of the Nathorst-Kolthoff Expeditions' L3'Codes than 

 the four I have here referred to L. eiidipleurosiicius, but after a personal inspection of the specimens in question I have not 

 been able to confirm this statement. In L. frigidiis on the other hand, the posterior margin of the pectoral is often 

 weakly incised. 



