8 G Canadian Arctic Expedition, 1913-1918 



of the specimens from Bernard harbour, July 3, 1916, had the greenish lustre typi- 

 cal of this species, the youngest ones being most transparent, but without the 

 orange main colour characteristic of the still earlier stages (Sars, 1896, Johansen, 

 1911), except for the intestine. A photograph of a part of the pond in which 

 they occurred is given on p. 7 in the report on Cladocera (Part H) in this volume; 

 they were not found in the north-end of the large pond, perhaps because a stony 

 shoal separates it from the deep part of the pond, where we may assume the 

 animals take refuge when the new ice begins to form in the fall, nor in the other 

 adjoining, large pond. I did not notice many individuals, and their place of 

 occurrence was limited to the shallow bights filled with water mosses and detritus 

 bottom along the grassy margin of this part of the pond. Their behaviour was 

 quite as described on p. 7 and it is fair to assume that they represent the 

 brood of the year (1916), and thus are about one month old. 



The specimens from a lake inland at the same locality, August 10, 1915, 

 had a length of from 8 to 15 mm. (carapace 6 to 1Q| mm.). Only the biggest 

 one had a few almost ripe, rose-purple eggs in the pouch (11th leg pairs), while 

 the others had unripe, whitish eggs. I kept them alive for a while, and noticed 

 how they devoured the fairy shrimps (Branchinecta paludosa) found in the same 

 lake. The latter was a typical large tundra pond or lake situated on the lowland, 

 with a stony or muddy (detritus) bottom with many bights with Carex-vegeia.- 

 tion. Its depth was not ascertained, but probably less than one fathom. 



The specimens from August 16, 1915, were secured in the same pond as 

 those from July 3, 1916 (see above), and measured from 7 to 15 mm., the largest 

 specimens having the cercopods 9 mm. long. Two of the 15 mm. long (cercopods 

 7-8 mm.) specimens I consider to be males (after an examination of their 11th 

 pair of legs), though Sars states (1896, p. 76), that the male attains a length of 

 only 13 mm. They are the only males I observed with certainty during the 

 expedition, though it is of course possible, that some of the younger individuals 

 (say less than one centimeter in length) secured, are males. Their occurrence 

 at Bernard harbour in the middle of August agrees with what is known from 

 Norway (Sars, 1896) and Greenland (Brehm, 1911), as mentioned p. 5. I 

 give here an outline (text figure 1^) of the shape and armature of telson in the 

 youngest (7 mm. long) specimen, and refer to my remarks, pp. 5-7. Only a few 

 of the 40 females secured (August 16, 1915) had a couple of eggs in the pouch 

 (compare p. 7), so perhaps they had been largely deposited now, on water- 

 plants, etc. 



The pond in which these were found had on October 6, 1915, ice 7 inches 

 thick over a water depth of 9 inches. Frozen into the ice I noticed many Lepi- 

 durus arcticus of all sizes, often found around air-bubbles enclosed in the ice at 

 varying depth. By chopping them free and later thawing out I ascertained 

 that all the animals were dead, but the full-grown females all had in each leg 

 pouch (11th pair) at least one, dark-purple, ripe egg (I5 mm. in diameter). I 

 placed these eggs to rearing, and cojlected more in the beginning of June next 

 year, but though kept until next July they did not hatch. I also cut a hole 

 through the ice about in the middle of this pond and secured two females Lepi- 

 durus, 10 and 12 cm. long,i which were swimming actively around under the ice, 

 though there were only a few inches of water here (temperature 33° F., air 

 24° F., 1.30 p.m.). None of them had any eggs in the leg pouch, and the larger 

 specimen was shedding its skin, the abdominal half of the animal having alreadv 

 grown a new cuticula. I give here (text figure Ih) an outline of the shape and 

 armature of the telson of both individuals (see pp. 5-7). 



The only Lepidurus I could find at Bernard harbour in June were a few, 

 dead, full-grown females with ripe eggs in the leg-pouch collected on June 6, 

 1916, m the same pond' as where I had collected them before (see above). 



1 Cercopods half the body-length. 

 ' Now already free of ice. 



