. Report of the Canadian Arctic Expedition 1913-18. Scientific expeditions. Cladocera 5 e Daphnia longispina var. hyalina forma arctica nova forma. Six plankton catches (vertical hauls) obtained from big lake (see fig. 3) at Bernard harbour, Northwest Territories, between September 30, 1915, and June 12, 1916, contain a diminutive form of the variety hyalina which is characterized chiefly by its small size. The crest of "this form is small and regularly rounded so that the eye is situated near the anterior margin and only a little below the middle of the head. The ventral margin of the he
. Report of the Canadian Arctic Expedition 1913-18. Scientific expeditions. Cladocera 5 e Daphnia longispina var. hyalina forma arctica nova forma. Six plankton catches (vertical hauls) obtained from big lake (see fig. 3) at Bernard harbour, Northwest Territories, between September 30, 1915, and June 12, 1916, contain a diminutive form of the variety hyalina which is characterized chiefly by its small size. The crest of "this form is small and regularly rounded so that the eye is situated near the anterior margin and only a little below the middle of the head. The ventral margin of the head is slightly concave and the dorsal margin of the shell shows a slight concavity just above the heart. (See figures 1 and 2.). Fig. 1.—Daphnia longispina var. hyalina forma arctica nov. forma. Big Lake, Bernard harbour, Northwest Territories, September 30, 1915. Length, exclusive of spine, mm. The egg-bearing females obtained in September range in length from 0-9 mm. to 1-0 mm., exclusive of the spine, while the February specimens vary from 0-7 mm. to a little more than 0-8 mm. The spine is from a half to two- thirds as long as the body. No ephippial females were noted in any of the catches from this lake, but six of the samples contained parthenogenetic females; the majority of the latter carried only two eggs while a few bore as many as three, and others only one. Wesenberg-Lund also found that the parthenbgenetic females of Daphnia longispina belonging to the microcephala- galeata group, in plankton material from Thingvallavatn lake, Iceland, carried but two or three Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Canadian Arctic Expedition (1913-1918). Ottawa, F. A. Acland, Printer to the King
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