7lG TACK SKOGSBBRG 



very closely related to (J. borealis (4. 0. Sars — ,,C*. horealis, 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 con- 

 siderably more robust." 



(4. (). Sa1!S writes (19U(), p. 128) with regard to C. maxima: ,,This form is very closely 



allied to . . . C. horealis. 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. < )n a closer comparison, 



some minor differences may also be found to exist in the structure of the several appendages." 



Ct. W. Muller 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. Ill and 1912, 



p. 87. This view has been adopted by P.T.Clem-:, 1903 and V. VAvra, 1906. Other writers 



have, as we have seen above, accepted the species established by G. S. Brady and A. M. NORMAN. 



■ ^^^lich 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 certainty. 



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 disposal. At j^resent it seems to me most 



probable that C. maxima is not quite identical with C. horealis. The differences between the 



forms in c[uestion are, however, so small that it seemed to me to be best to put the former as a 



variety of the latter. i1 



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. Muller'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 ('. horealis is, of course, striking. 

 The maximum length for the latter species is ^ = 2,35 (V. VAvra), $ = 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 exceedinglv probable, is very decidedly ojDposed, however, by the fact that I found 

 a typical mature C. horealis 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 ('. horealis; the male 

 measured, as is seen above, 2,3 mm., the females 2,4 — 2,7 mm., i. e. the latter were even some- 

 what smaller than the Lofoten specimens. It was these finds especially that caused me not 

 to follow G. W. Mullein's example of imiting these two forms entirely. 



The posterior edge of the shell of the mature male is in most cases somewhat less rounded 

 in tlie maxima form than in the horealis form; cf. pi. XXXV, fig. 3, G. 0. 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 horealis. On account of this the shell, when seen from the side, gets 

 a straioliter dorsal margin in the foriner form; see (i. O. Sahs'.s figs., 1900 ;md (J. W. Mi'I-EER's 



