6 N Canadian Arctic Expedition, 1913-1918 



(coUembola, dipterous larvae, dytiscids, etc.)- Interesting, however, was the 

 occurrence of Mesidothea entomon in a deep pool in the outlet from the large lake 

 here to the sea, as recorded in the report upon the Isopods collected during the 

 expedition (Vol. VII, Part D, p. 21). Apparently these Crustacea had reached the 

 pool, which had fresh water, when it was connected temporarily with the sea 

 at high tide. In this connection it is also of interest to observe, that the common 

 marine littoral amphipod (Gammarus locusta) in the parts of the arctic coast 

 investigated, as well as along the coasts of both the New and the Old World, at 

 high tide often ascends to lagoons and outlets of rivers or brooks; and when 

 left there by the sea receding, seems to thrive well, and thus may be termed a 

 brackish water form, though not so typical a freshwater species as Gammarus 

 limnaeus and Synurella johanseni. 



There is an extensive salt water bight, separated from the harbour by 

 two sandbars and a very shallow (1-2 feet) entrance, at Collinson .point in 

 Camden bay. The water in this lagoon is, however, deep enough to permit 

 of the existence in it of true marine fishes and invertebrates, some at least 

 belonging to littoral and planktonic forms; that is to say individuals which 

 happen to get in through the entrance, which is almost dry at low tide. 

 I have observed many times how effective is the renewal of marine life in this 

 lagoon bight; even large Mesidothea being whirled out or more often in 

 at the changing of the tides. The maximum depth of this lagoon bight 

 does not reach one fathom, and it begins to freeze over considerably 

 earlier (middle of September, 1913), than the bay or ocean outside. It freezes 

 solidly to the bottom during the winter, and melts again next June. No fresh- 

 water streams, apart from melting snow in May-June, enter this lagoon bight, 

 and it contained no freshwater life.^ 



No true lagoons are found at Collinson point proper, but several "beach 

 ponds" occur. As is the case both east and west of this place a great amount 

 of driftwood has been washed up on the beach (or former beaches), and together 

 with the sand or gravel upon which it rests it bars the access of the sea or 

 streams to these waterholes or ponds, which owe their origin mainly to snow 

 accumulations and diffusion from the surrounding soil. Such a typical beach 

 pond was investigated at Collinson point on June 22, 1914. The bottom was very 

 uneven, owing to its being filled up with driftwood, which also surrounded 

 it on all sides. Some parts of it were quite or nearly dried up; other 

 parts were deeper, but I doubt if there is any water at all in it during 

 the latter part of the summer (August). So it may perhaps better be termed 

 a waterhole. The water in it was slightly brackish, and where exposed to the 

 sun it had a temperature of 50° F. (air 41° F.), at 5.30 p.m. Vegetation (grass, 

 mosses, etc.) was found in parts of the pond, but its sides and bottom were 

 mostly made up of brown mud (organic detritus) and driftwood. On that day 

 (June 22) this waterhole was swarming with thousands of young fairy-shrimps 

 (Branchinecta paludosa) now in the metanauplii stages, and especially congre- 

 gating in the muddy, sun baked parts of the pond. In addition a great number 

 of Chironomus larvae in their mud tubes were attached to the submerged drift- 

 wood or moved over the bottom; but otherwise the pond had little life. The 

 same species of fairy-shrimps were also found to be numerous in a still smaller 

 waterhole, the remnant of a dried up lagoon pond, near the beach and on the 

 same level a little west of the beach pond described above, on July 11, when 

 the temperature of the water in this small hole was 58° F. at 6 p.m.; 

 This phyllopod was not found in other ponds or waterholes at Collinson point, 

 and Lepidurus arcticus in none. Mr. Jenness brought me, however, a few 

 specimens of both these species, Lepidurus collected on June 7, 1914, and 

 Branchinecta July 17, 1914, in pools on Barter island, which may be said to 

 form the eastern end of Camden bay, and is only a short distance from Martin" 

 point. In the middle of July the two waterholes at Collinson point mentioned 



' See Plate V., on meridian ot 144° 50' W. longitude. _ 



