12 N Canadian Arctic Expedition, 1913-1918 



was not observed in the locality in question from September to May inclusive. 

 The growth of Branchinecta paludosa from the nauplius to the mature male or 

 female is sufficiently rapid (about a month) to allow the species to deposit the 

 fertilized eggs before the complete drying up of the pond in which it is found, 

 and long before its freezing up later in the fall. 



While the shallow ponds at Bernard harbour are very similar to the others 

 occurring all along the arctic coast the small, brackish pond on the south side 

 of the outlet of the large creek just west of the station presents some peculiar 

 and interesting features. The pond is situated on gravel and sand flats at only 

 a few feet elevation and surrounded by vegetation composed almost exclusively 

 of a minute Carex (C. subspathacea) . When the snow is melting rapidly it receives 

 some additional freshwater from the slopes behind, and the overflow has 

 excavated a fairly deep and wide channel between the pond and the beach nearby. 

 During the summer and until the snow falls the outline of the pond is however 

 well defined (see Plate II). The pond consists of a deeper (up to one fathom) 

 hole in the middle, bottomed with a thick layer of black, stinking mud, and very 

 shallow ( a few inches deep) marginal water, extensive in the early summer, but 

 rapidly drying up under the influence of the sun later. It contains a rich 

 animal life, conaposed of Entomostraca (Branchinecta paludosa, Daphnia pulex 

 and copepods), aquatic insects, etc., more or less restricted to the masses of 

 green filamentous algae found in the water. The bottom of the marginal water 

 area of the pond is covered with light brown detritus mud.' 



It has been mentioned above, that the brackish nature of the water in this pond 

 had little influence upon its content of invertebrates; this is further emphasized by 

 my finding the same Entomostraca, etc. {except Daphnia pulex), in a much smaller, 

 shallow, brackish pool near the coast a little further west and north in the middle 

 of July, 1916. The sahne nature of the water in this latter pool was 

 shown by its taste and the presence of certain marine algae (Fam. Ulvaceae), 

 besides the common green filamentous algae, typical of freshwater. In this case 

 the distance from the beach yfus so insignificant, and the pool so small and 

 shallow, that its formation is to be attributed to a slight, and fairly recent, 

 raising of the sea shore. 



The three larger lakes situated west and south of our winter quarters at 

 Bernard harbour have already been referred to. The two most westerly ones of 

 these are the biggest, though only their east ends are shown on the detail map. 

 The most northerly is situated about 35 feet above sea level some distance 

 inland, and has an outlet to the sea through the large creek already mentioned. 

 Another creek flows into the south side of the lake, carrying the overflow from 

 the lakes and ponds situated inland there, and probably also from the west end 

 of the large lake described just below. The large lake in question may be 

 considered merely a widening of the creek coming into and out from it, and is 

 almost entirely surrounded by swampy tundra, thus resting in an extensive 

 valley, bounded here and there by low ridges. In the beginning of October, 1915, 

 I took a number of soundings from the 9-10 inches thick fall ice across the 

 middle of the lake, from the big boulder near its south shore to a grassy point 

 opposite, on the north shore. The result is given in the following table 

 (maximum depth in italics) : — 



Bottom brown sand 



^See Part A, Vol. IV of these reports- 



