Bd. V: 6) THE FISHES OF THE SWEDISH SOUTH POLAR EXPEDITION. 63 
This species is closely allied to Myctophum arcticum (Lütken ) 1 2 described from 
off the Greenland coast, but differs from the same in the following point. The 
number of anal rays is large, about 21, but only 17 in M. arcticum. AO. are 18 
in this new species, only 15 — 16 in M. arcticum , and as already stated the Prc. sit 
farther apart. The different arrangement of the SAO. is already mentioned. I have 
not had any specimen of M. arcticum for comparison, but, to judge from LüTKEN’s 
figure (1. c. p. 249), it seems to have a considerably wider interorbital space than the 
new species. The relative dimensions of the head are also different. In a specimen 
measured by LÜTKEN, and of the same size as this one, the length of the head was 
contained 3V5 times in the total length, and according to a communication, kindly 
given me in a letter by my friend Professor AuG. Brauer, he has found the rela- 
tion between the length of the head and the total length in another specimen of 
M. arcticum to be 1 : 3,3. These differences appear to be so important that, if the 
different geographical distribution as well is put in the scales, there can be no doubt 
of the specific value of the fish described above. But it is of exceedingly great 
interest to find that the Greenland seas and the Southern Atlantic are inhabited by 
two so closely related forms which even show a ’’such biological affinity as the ex- 
centric situation of the lens of the eye indicates. 
5. Myctophum affine (LÜTKEN). 
i specimen caught at the surface where the temperature was + 21,9" C. nth 
of Dec. 1901. 32° 15' S. lat. 50° 14' W. long. 
The collection of this expedition contains only a single and small specimen of 
this species from the mentioned locality. But it is otherwise known to be very 
widely distributed as already LÜTKEN 2 could enumerate many localities from the 
Indian Ocean. Later the authors of the “Oceanic Ichthyology” could record their 
M. opalinum from many other localities in the Northern Atlantic off the North 
American coast. M. nitidulum GARMAN is very similar to this one and, if not 
identical, it seems to be only a geographic subspecies of M. affine found in the 
Pacific: 27 0 50' N. lat., 145 0 45' 30" W. 
The above recorded locality appears to be the most south-western where this 
species has been hitherto collected. 
1 Spolia Atlantica. Scopelini. K. D. Vidensk. Selsk. Skr. 6 Række T. VII. Kjöbenhavn 1892. 
2 Spolia Atlantica 1 . c. p. 252. 
