26 



The Canadian Field-Naturalist. 



[Vol. XXV 



As to the southern boundary of the dis- 

 tribution of B. paludosa on this continent 

 little is known ; but the records of it from 

 Commander Islands, Siberia (Lilljeborg, 

 and the Pribilofs (U.S.N.M.) indicate that 

 it is found at least upon some (western?) 

 of the Aleutian Islands. Also, some young 

 ones were collected by J. M. Jessup in a 

 puddle at Whitehorse, Yukon Territory, 

 June 7, 1912 (Pearse, , 1918). I did not 

 observe it at Nome or Teller, Alaska, but 

 it was found by Murdoch at Point Barrow^ 

 in the same pools as PolyartemieUa hazeni. 

 I found it very common along the coast 

 from Camden Bay to Demarcation Point, 

 Alaska, and also on Herschel Island, Yukon 

 Territory, in the summer (June- August) 

 of 1914. It was also collected by J. M. 

 Jessup in Muskeg Lake (lat. 6940'N. long. 

 141=AY) on July 25, 1912 (Pearse, 1913). 

 We may, therefore, perhaps assume that it 

 occurs over the Avhole of Alaska and the 

 Yukon Territory, except the southern part 

 of the former, at a certain time of the year, 

 and where suitable ponds or lakes are pre- 

 sent. Dr. J. Rae brought back from Cape 

 Krusenstern, Dolphin and Union Strait, 

 Northwest Territory, some fragments of 

 botli sexes collected in August, 1849; they 

 were referred by W. Baird to this species. 

 According to the great number of observa- 

 tions and collections of this species by me 

 in 1914-16 in this locality (Bernard Har- 

 bour) there can hardly be any doubt about 

 it, an opinion also expressed by Verrill and 

 Packard. It was further secured (Sars) 

 by the "Gjoea" Expedition (Amundsen) 

 on the south side of King William Land, 

 in 1904 and 1905; by the "Neptune" Ex- 

 pedition at FuUerton on the west side of 

 Hudson Bay in 1903-04 ; by Turner in pools 

 on rocks at Fort Chimo, Ungava; by Pac- 

 kard in August, 1864, and by Bryant in 

 1908, at Hamilton Inlet in Labrador; by 

 the Second Norwegian Arctic Expedition 

 on Johan Peninsula,, Ellesmere Land, in 

 1898-99; by Hart at Discovery Bay (lat. 

 8141'N.) and by the Princeton Expedi- 

 tion, 1899, at Cape Sabine, on the west 

 side of Grinnell Land. In west Greenland 

 it has furthermore been recorded from a 

 number of places up to Polaris Bay (about 

 lat. 82 N.), where it was taken by Bessels 

 in August 1872, (Packard), and on Nor- 

 thumberland Island, (Ortman). There 

 can therefore be little doubt that it occurs 



upon all the islands composing the Can- 

 adian Arctic Archipelago. 



The structure and biology of this species 

 has been so well treated and figured by G. 

 0. Sars in his monumental Avork (1896) 

 that I need only refer briefly to the life- 

 history. The additional observations I was 

 fortunate to make during my stay along 

 tlie arctic coast of northwest America with 

 the southern party of the Canadian Arctic 

 Expedition 1913-16, will be found in the 

 reports of the said expedition (Volume 

 VII, Part G). Suffice it to say that its 

 whole life-history is now known, because I 

 secured in the north still earlier stages than 

 Sars' metanauplii (see his Tab. VIII) and 

 actually succeeded in rearing in the spring 

 the nauplii from hibernating eggs kept all 

 through the winter. Its life-history is, 

 therefore, the following, at least in the 

 arctic part of northwest America. The 

 hibernating eggs frozen in the ice, hatch 

 out a little after the latter melts in the 

 spring or early summer (June), and the 

 nauplii and metanauplii continue to grow 

 until at the end of July or beginning of 

 August they are sexually ripe. The copu- 

 lation and laying of the eggs then takes 

 place during August and part of September, 

 until the water freezes and kills them all 

 except the eggs. Apparently, however, a 

 great number of the adults die a natural 

 death from the middle of August on, pre- 

 sumably when copulation and egg-laying 

 is over. That they are also killed off by 

 other causes (enemies, waves, drying up 

 of the ponds) has already been referred 

 to. The earliest records in the year I have 

 from this coast is Chantry Island, June 

 17, 1916, (a couple of nauplii and many 

 metanauplii), and the latest record is adults 

 of both sexes from Bernard Harbour, Aug- 

 ust 23, 1915 (specimens kept). 



Mr. A. Halkett writes in his field-notes 

 from the "Neptune" Expedition, that 

 female phyllopods of this species (identi- 

 fied by Prof. G. 0. Sars of Christiania, 

 and by me) were collected in ponds at Ful- 

 lerton on the west side of Hudson Bay as 

 late as the end of October and the begin- 

 ning of November, 1903. The water-depth 

 of one of the ponds was about seven feet, 

 and they were then all covered by ice^ 

 which in the last days of October was of a 

 thickness of about one foot. The temper- 

 ature of the air was about zero, and that 



