l'(j()li COD. 



499 



Throughout this table, whore the nverages in (lU- 

 (las minutus increase with age, the averages are greater 

 ill (iadus htsctis than in the former species; and where 

 tlie averages decrease with age in Gadtis minuftifi, they 

 are also less in (Iddus Iiisck.s. 'I'hus the two species, 

 if one chooses to call thcni so, stand in a very intimate 

 developmental relation to each other; and the gaps be- 

 tween the maximum and minimum proportions given 

 al)o\e Avould no doubt liavc l)een tilled in most cases, 

 if not in all, if we had been enalded to examine 

 ^■ou^lger specimens of Gadus luscus. Between the largest 

 specimen of Gadus minutus (210 mm. long) in the 

 possession of the Royal Museum and the smallest 

 specimen of Gadus luscus (297 mm. long) the gap 

 is sufficiently wide to admit of considerable changes 

 of growth. 



We have just seen how Gadus naraf/n and G. ffra- 

 rilis afford the same example of almost identical forms 



whose right to the position of independent species may 

 well be questioned, the resemblance between them being 

 so close that the existing differences may well be re- 

 garded as the expression of local variations. The case 

 is the same here. The true home of the l»ib evidently 

 lies round the British coasts, for to the north and south 

 it becomes rarer and rarer, the further we go fi-om this 

 centre; but in Scandinavian waters and, still more fre- 

 quently, in the Meditei'ranean its juvenile stages occur 

 with a certain degree of independence in form and 

 colour. That these younger forms, even in English 

 waters, should keep apart from the older ones, at dif- 

 ferent depths and, in most cases, on different bottoms, 

 coincides with our knowledge of tlie otlicr Codtishes 

 at different ages. Finally, to judge by the observations 

 made up to the present, the Mediterranean capelan is 

 distinguished from the Scandinavian Pooi' C"od only by 

 its still closer affinity to the Bib. 



The following group in the Scandinavian fauna 

 contains three species, one of which, Gadus Esniarkii, 

 never attains the same size as the others, and retains 

 several characteristics in common with their juvenile 

 stages. Still, it is distinguished from them in several 

 respects by the distinct direction of its development, 

 and also by the persistency of the barbel under the chin 



even in its adult state. Gadus Esniarkii thus ranges 

 itself nearer the common origin of all the Cods; and 

 of the true Coalfishes, the Pollack and the Coalfish, the 

 latter is the further advanced in those respects in which 

 all three species show a common direction of development. 

 This appears most distinctly, according to our investi- 

 gations, in the following respects: 



Average in 



Gadus Esmarkii. 



Gadus pollachius. 



2 

 ecimens. 



speontens. | specimens. 



speeii 



Gadus virens 



.8 I 2 

 specimens. ! specimens. 



Length of the body expressed in millimetres Ill 



Least depth of the tail in % of the length of the lower jaw .._ ] 30.1 



Length of the snout ,, ., ., ,, ,, ,, ,. ., „ 1 jO-3 



173 

 33.2 

 53.3 



'-'(.14 

 40. s 

 56.0 



41.1 

 58.9 



1(1.-. 

 43.7 

 65.1 



300 

 44.9 

 G9..1 



