38 | Sigurd Johnsen. 
temperature, the reduction of size and in the number of vertebræ 
came out more strongly here as is nowadays shown by the rest 
of this stock living in the Marmora Sea. 
Besides M. glaciale the ,Thor“ caught only two other 
Myctophids in the Sea of Marmora. Of these M. benoiti is 
distributed throughout the Mediterranean and its occurrence in 
the Marmora is thus easily accounted for. Not so with the 
other species M. (Lampanyctus) crocodilum. According to Taning 
(1918 p. 117, fig. 42) only one adult and 10 postlarve were 
taken in the Sea of Marmora, none in the Ægean nor in the 
eastern basin proper whereas it was generally distributed through- 
out the whole western basin (58 adult and 1077 postlarvæ). 
The material from the Marmora is too scanty to permit any safe 
conclusion as to the occurrence of the species there, whether we 
have to do with an isolated stock (like that of M. glaciale) or 
whether the Marmora specimens are connected with the rich 
western stock through a sparse occurrence (hitherto unobserved) 
in the eastern basin and the Ægean. I am inclined to take the 
former view. M. crocodilum shows indeed considerable simi- 
larity to M. glaciale in its horizontal distribution outside the 
Mediterranean. It is at present only known from the eastern 
Atlantic, ranging from the Azores to Ireland, where acc. to 
Holt & Byrne (1911 p. 26 and 20) this species and M. punctatum 
are the commonest Myctophids next to M. glaciale, larvæ as well 
as adult ones being known. 
The Myctophids of the Mediterranean, which as typically 
oceanic fish must have immigrated from the Atlantic, are both 
as to number of species and to number of individuals most 
richly represented in the western basin, and the species which 
are known to occur in the eastern basin generally are of a 
southefn range in the Atlantic. It is therefore a remarkable 
coincidence that those two species (out of three) which have 
penetrated as far as the Sea of Marmora are both ranging farther 
north in the Atlantic than Myctophids generally do. 
The view here set forth concerning the occurrence of 
M. glaciale in the Mediterranean waters is in my opinion further 
supported by a biological feature presented by the species there. 
As mentioned before the spawning in the Atlantic takes place in 
spring, while the Mediterranean race spawns not only in winter 
