20 SMITT, ON THE GENUS LYCODES. 



first iu the typical rcticulatus that we find the character, 

 which by Collett was assigned to Lycodes Liithenii^ 



After this examination of the most principal characters, 

 it may well be conceded, that among our true Lycodes the 

 distinction of species is very vagiie. It seems rather as if 

 the species still were in a state of developing themselves. 

 In the larval and in the yonng postlarval stages they are rather 

 impossible to distinguish from each other, but the individual 

 varieties seem to leave a great iield for the working up of 

 more stabile differences. Such a difference, constant enough, 

 althongh of no considerable magnitude, we have ascertained 

 between the resp. limits of variation in the old Reinhardtian 

 species Vahlii and reticulatus. As the natural factors for 

 their differentiating themselves from each other, in connection 

 with the evolntional force, in many instances we have seen 

 the feminine characters leading the way of differentiation to 

 Lycodes VaJilii, the masculine characters leading to Lycodes 

 reticulatus. Within the limits of the former species it is 

 easy enough to distinguish a local form, gracilis, living in 

 the more southerly localities on the european side of the 

 Atlantic, corresponding to the £oarchus-iorm. on the american 

 side, and perhaps by this geographical selection from the 

 true home of the genus stopped in the evolution and retaining 

 the juvenile characters. Again within the limits of variation 

 of reticulatus, a special form, frigidus, may have been origi- 

 nated, perhaps by hybridisation, in the arctic home common 

 for the two species. The resp. differences between x^allidus 

 and Vahlii and between seminudiis and reticulatus are of still 

 less value or constancy: they may rather be regarded as elong- 

 ated varieties, with indications of a farther differentiation, 

 that may perhaps lead to the origin of distinct species. 



We thus arrange the forms: 



A: Length of the head more than 41 per cent of the length of the tall. 

 a: Median lateral line most conspicuous. 

 a: Height of the body at the beginning of 

 the anal fin usually more than 22 per 

 cent of the distance of this fin from the 

 tip of the lower jaw Lycodes reticulatus. 



1 Norsk Nordh. Exped. 1876-78, Zool., Fiske, p. lOa. 



