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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”
(between D3 and A2), the southern has 3: one at the end of the tail, one between D2 and
A1 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
species. 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 Gadiculus
argenteus 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 fin-rays also showed agreement.
That the 3 specimens from Naples really belonged to Guichenot’s Gadiculus
argenteus, I was able to prove from a direct comparison with one of Guichenot’s type
specimens, which Prof. Louis Roule, Muséum 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
primary pigment, as that found between specimens from the Mediterranean and the
Atlantic, 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 hand,
I possess well over 3000 postlarval specimens from the cruises of the “Thor” in
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