42 0. NORDGAARD. [2nd ARC. EXP. FRAM 



may be worth while to find out in which direction this difference mani- 

 fests itself. 



In the arctic fauna, there is only one species of the Genus Cellaria, 

 namely, C. articulata, Fabr. (C. borealis, Busk). This genus also 

 seems to be especially associated with the southern hemisphere. This 

 is possibly connected with the circumstance pointed out by F. Canu, 

 that the Bryozoan fauna of the southern hemisphere is of an old charac- 

 ter ^ Among the British Cellaria species, C. fistulosa, Lin. is of recent 

 distribution from Malangen Fjord in the north of Norway to Australia 

 and New Zealand, and the species is found in a fossil state in Tertiary 

 deposits in S. W. Victoria (Waters) and in the Eocene of Calabria 

 (Neviani). C. sinuosa, Hassall, has not such a wide recent distribu- 

 tion, but is found in fossil state in the Crag (Busk), in the Italian 

 Pliocene (Manzoni), and in Tertiary strata in South Australia (see Hincks, 

 B. M. P ., p. 110). C. johnsoni, Busk, has been found in the pre- 

 sent day from Shetland to Madeira, and in the fossil state in the Cala- 

 brian Miocene (Neviani). The genus Cellaria occupy a somewhat iso- 

 lated position in the present fauna, and for this reason alone, one is 

 inclined to look upon it as a veteran genus. Waters^ says moreover 

 that he has come to the conclusion „that Cellaria and Onychocella 

 branched from a common ancestor before the Cretaceous". But it is not 

 easy to arrive at any certain result with regard to the age of the various 

 species. As far as I know, C. articulata has not been found as a 

 fossil ; and it is possible that it has originated from some Tertiary pri- 

 mitive form or other, and has little by little established its characters 

 under the severe natural conditions which took the place of the mild 

 climate of the Tertiary Period. The comparatively limited field of its 

 distribution may also possibly be regarded as an indication that the age 

 of the species is not very great. The distribution of a species ought 

 scarcely to be looked at only in the light of the hydrographic conditions. 

 It thus appears to be a more or less general rule that a wide distribu- 

 tion in time corresponds with a wide distribution in space. While Hincks 

 and Robertson state that C. articulata is abundant at Queen Charlotte 

 Islands, and according to the descriptions of several investigators, is 

 thought to be quite common off Greenland, and was found by the 2nd 

 Fram Expedition in several places on the east side of Hell Gate, there 



„Un caractere nettemenl archaique quand on considere les genres surtout". Cf. 

 F. Canu, Les Bryozoaires du Patagonien, p. 5. Memoires de la Sor,. G6ol. de 

 France, Paleontologie, vol. 12, fasc. 3, mem. no. 33. Paris, 1904. 

 Bryozoa, p. 36. Exp6d. Antarclique Beige. 



