162
ANTON F. BRUUN
Ix. PARALLEL CASES AMONG NORTH ATLANTIC APODES
While studying the leptocephali of the two North Atlantic species of
Anguilla, Schmidt at the same time collected probably at least 100 000
specimens of leptocephali of other species of Apodes. He published
many studies on these ; but here we may only discuss his findings
regards the two North Atlantic species, Conger conger and C. oceanicw
Mitchell (Schmidt, 1931).
Schmidt had about 2500 larval Conger and gave the number of
myomeres in 201 C. conger as varying between 154 and 163, average
158.2, while 288 larvae of C. oceanicus showed 140 to 149, average
144-6 myomeres. The distribution of the leptocephali of the two
species is a striking parallel with that of the two species of Anguilla,
except that Conger conger, as Schmidt points out, breeds along the
whole extent of the area from the Sargasso Sea to the eastern part of
the Mediterranean ; throughout this extent he found tiny larvae, only
10 mm in length, always over great oceanic depths. As to C. oceanicw,
Schmidt found quite tiny larvae in the West Indies, indicating a breeding place there.
From this it is obvious that Conger requires a much less special
environment for its spawning than Anguilla. This is also borne out by
the fact that Schmidt found leptocephali of a third species of Conger in
the South Atlantic, off Argentine, where no Anguilla species occurs.
Tucker (1959a, p. 497) states: “ In the Mediterranean, again, are
several deeps which offer conditions apparently identical to those of the
Sargasso, yet eels do not spawn in them nor anywhere in that Sea. In
the open Atlantic the Cape Verde Basin, Monaco Deep and West
Indian Basin, all on the obvious migration route, are likewise devoid
of young larvae.”
It is very easy to show that all these areas each have quite characteristic features of their own ; it is in fact more easy to point at differences than a t similarities in their hydrographic structures. For the
time being we can only consider Conger and Anguilla as one example
out of very many which discriminate in different ways in the choice of
breeding places.
In 1937 I added two more cases similar to Anguilla and Conger,
namely that of Synaphobranchus kaupi Johnson and S . infernalis Gill
and of the two very closely related Leptocephalus species L. euryurw
Lea and L. similis Lea.
The parent species of the two last mentioned species are not known
with certainty ; but as regards the adult Synaphobraltchus I definitely
know that they are of bathyal and abyssal distribution; so it is no
wonder that the bottom-dwelling adolescent and adult stages have
ANTON F. BRUUN
Ix. PARALLEL CASES AMONG NORTH ATLANTIC APODES
While studying the leptocephali of the two North Atlantic species of
Anguilla, Schmidt at the same time collected probably at least 100 000
specimens of leptocephali of other species of Apodes. He published
many studies on these ; but here we may only discuss his findings
regards the two North Atlantic species, Conger conger and C. oceanicw
Mitchell (Schmidt, 1931).
Schmidt had about 2500 larval Conger and gave the number of
myomeres in 201 C. conger as varying between 154 and 163, average
158.2, while 288 larvae of C. oceanicus showed 140 to 149, average
144-6 myomeres. The distribution of the leptocephali of the two
species is a striking parallel with that of the two species of Anguilla,
except that Conger conger, as Schmidt points out, breeds along the
whole extent of the area from the Sargasso Sea to the eastern part of
the Mediterranean ; throughout this extent he found tiny larvae, only
10 mm in length, always over great oceanic depths. As to C. oceanicw,
Schmidt found quite tiny larvae in the West Indies, indicating a breeding place there.
From this it is obvious that Conger requires a much less special
environment for its spawning than Anguilla. This is also borne out by
the fact that Schmidt found leptocephali of a third species of Conger in
the South Atlantic, off Argentine, where no Anguilla species occurs.
Tucker (1959a, p. 497) states: “ In the Mediterranean, again, are
several deeps which offer conditions apparently identical to those of the
Sargasso, yet eels do not spawn in them nor anywhere in that Sea. In
the open Atlantic the Cape Verde Basin, Monaco Deep and West
Indian Basin, all on the obvious migration route, are likewise devoid
of young larvae.”
It is very easy to show that all these areas each have quite characteristic features of their own ; it is in fact more easy to point at differences than a t similarities in their hydrographic structures. For the
time being we can only consider Conger and Anguilla as one example
out of very many which discriminate in different ways in the choice of
breeding places.
In 1937 I added two more cases similar to Anguilla and Conger,
namely that of Synaphobranchus kaupi Johnson and S . infernalis Gill
and of the two very closely related Leptocephalus species L. euryurw
Lea and L. similis Lea.
The parent species of the two last mentioned species are not known
with certainty ; but as regards the adult Synaphobraltchus I definitely
know that they are of bathyal and abyssal distribution; so it is no
wonder that the bottom-dwelling adolescent and adult stages have