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very closely related to C. boreal is G. 0. Sars — „C. borealis, which it very closely resembles“.
The following differences between these two forms are noted in the work just mentioned:
„C. maxima is rather larger and the shell is not so densely reticulated. The outline of the shell,
seen dorsally, is different, and the spinules of the principal seta of the male antennule are
considérable more robust.“
G. 0. Sars writes (1900, p. 128) with regard to C. maxima: „This form is verv closely
allied to . . . C. borealis. It is, however, of larger size, and differs, moreover, in the less strongly
marked sculpture of the shell, as also somewhat in the form of the latter. On a doser comparison,
some minor differences may also be found to exist in the structure of the several appendages.“
G. W. MÜLLER in his work of 1901 put forward the view that the two forms are quite
identical; the same view is also taken by this writer in his later works, 1906 a, p. 111 and 1912,
p. 87. This view has been adopted by P. T. Cleve, 1903 and V. Våyra, 1906. Other writers
have, as we have seen above, accepted the species established by G. S. BRADA’ and A. M. NORMAN.
Which of these opinions is the correct one? Are these two forms quite identical or not?
It seems to me impossible at present to answer this question with complete certaintv.
To do this it would be necessary to carry out renewed and careful investigations on a considerably
more abundant material than that which was at my disposai. At present it seems to me most
probable that C. maxima is not quite identical with C. borealis. The differences between the
forms in question are, however, so small that it seemed to me to be best to put the former as a
variety of the latter.
The only quite certain difference I was able to find was that of size. G. 0. Sars states
that the male of C. maxima had a shell 3,20 mm. long and the female 3,50 mm. G. W. MÜLLER’s
males from Greenland measured 3,0—3,15 mm. The males of the maxima form investigated
by me had shells 2,95—3,2 mm. long; the females were 3.25—3,5 mm. long. The difference
between these figures and those previously given for C. borealis is, of course, striking.
The maximum length for the latter species is £ 2,35 (V. Vävra), Ç = 2,9 mm. May this
difference in size be connected with a difference in locality? Is the increase in size not merely
the result of a modification under Arctic conditions? This explanation, which may, of course,
seem a priori exceedingly probable, is very decidedly opposed, however, by the faet that I found
a typical mature C. borealis male as far north as lat. 79°58’N.; the length of shell of this male
was not greater than that of the specimens from Lofoten; cf. p. 708 above. At lat. 76° 36’ one
mature male and three mature females were found, all typical C. borealis; the male
measured, as is seen above, 2,3 mm., the females 2,4—2,7 mm., i. e. the latter were even
somewhat smaller than the Lofoten specimens. It was these finds especially that caused me not
to follow G. W. MÜLLER’s example of uniting these two forms entirely.
The posterior edge of the shell of the mature male is in most cases somewhat less rounded
in the maxima, form than in the borealis form; cf. pl. XXXV, fig. 3, G. O. Sars, 1900 and my
appended fig. 1; there is, however, not quite complete constancy with regard to this character.
The shoulder vault of the shell is, in both males and females of the maxima form, somewhat
less developed than in borealis. On account of this the shell, when seen from the side, gets
a straighter dorsal margin in the former form; see G. O. Sars’s figs., 1900 and G. W. Müller\s
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