6 Mindeskrift for J, Steenstrup. XIV. 



than the northern. Both these features can be recognised in all the stages, from the 

 youngest to the oldest. The most striking difference between the two species, however, 

 is the postanal pigmentation. Whilst the northern only has one "transverse bar" (be- 

 tween D^andA^), the southern has 3: one at the end of the tail, one between D^ and 

 A^ and a third intermediate, corresponding to that found in the northern species, We 

 find quite the same features in all stages of development, even in the smallest examined, 

 4 — 5 mm. long, that is, 3 postanal bars in the southern and only 1 in the northern spe- 

 cies. As is usual in the Gadus species, the characteristic distribution of the primary 

 pigment is effaced in the oldest, postlarval stages, new pigment gradually covering most 

 of the lateral aspects. Yet even in the oldest postlarval stages the northern species is 

 far less pigmented than the southern. 



The proof, that our postlarval stages belong to the Mediterranean Gadiciilus ar- 

 genteus Guichenot, lies in the complete agreement between them and older specimens 

 in the characters which are already permanently developed in the young, postlarval 

 stages, especially the number of vertebrae. 



In 3 adult specimens of Gadiculus argenteus from Naples the following number of 

 vertebrae was found: 13 + 27, 13 + 27 and 13+26, and in 3 postlarval specimens 

 taken by the "Thor" in the Western Mediterranean: 13 + 27, 13 + 27 and 13 + 26. 

 The number of fm-rays also showed agreement. 



That the 3 specimens from Naples really belonged to Guichenot's Gadiculus ar- 

 genteus, I was able to prove from a direct comparison with one of Guichenot's type 

 specimens, which Prof. Louis Roule, Museum d'Histoire Naturelle in Paris, kindly 

 placed at my disposal. I found complete agreement. The specimen possessed 27 caudal 

 vertebrae i. e. the number of most frequent occurrence in specimens belonging to the 

 southern species. 



It was thus evident, that the pelagic stages taken by the "Thor" Expeditions in 

 the Mediterranean and near Gibraltar belonged to Guichenot's species. At the same 

 time it was clear, that the postlarval Gadiculus from the Atlantic previously described 

 by me (1906) could not belong to Guichenot's species, as I then believed without knowing 

 specimens from the Mediterranean. Such a complete and typical difference in the pri- 

 mary pigment, as that found between specimens from the Mediterranean and the At- 

 lantic, must necessarily indicate a difference in species, to judge from the conditions 

 known in all the other allied, European species of the genus Gadus and in other northern 

 Gadoids. 



My material of the bottom-stages of Gadiculus from the Mediterranean is still sparse 

 and only contains specimens considerably smaller than the Gadiculus bottom-stages I 

 have from the waters west of the British Isles and the Skagerak. On the other hånd, 

 I possess well over 3000 postlarval specimens from the cruises of the "Thor" in 1905 — 



