Crustacean Life N 7 



above were much diminished in size and would plainly contain no water at all 

 at the end of the month. Unfortunately I did not ascertain this and what 

 became of the fairy-shrimps they contained, because we sailed eastward shortly 

 afterwards (July 24). 



The typical tundra ponds or lakes are very much the same all along the 

 arctic coast of northwest America, so it is not necessary to describe them, at 

 any definite locality of the coast west of Mackenzie river, except on Herschel 

 island (see later). In contrast to the beach ponds and lagoons they do 

 not depend to any extent upon the configuration of the coasthne of each 

 particular place, because they are generally found only at a certain distance 

 inland. There are, however, often ponds which represent a transition stage 

 between the beach ponds or lagoons and the true tundra ponds; and such ponds 

 are perhaps more likely than the freshwater bodies farther inland to contain 

 Phyllopods. The photographs taken of the ponds along this coast during the 

 expedition give a better idea of their appearance than many words of des- 

 cription.i 



Those of the tundra ponds which contain water all the year round, are 

 frozen to the bottom, unless they are more than one fathom deep, during 

 the winter, and are generally covered with a deep layer of snow, except where 

 the wind has removed this from spots on the ice surface. In the beginning of 

 May (observations from Demarcation point, 1914), the power of the sun on 

 clear, calm and warm days is so great that the ice in the very shallow ponds 

 begins to melt, and the dark mud bottom to thaw, though the temperature of 

 the strata (ice, mud bottom, dead leaves, etc.) on May 4 was only from 32° 

 to 32.5° F. (air 29.5° F.), and the ground was still frozen solidly. Large hiber- 

 nating, dipterous larvffi were then found in some of these ponds. The 

 further melting of the shallow ponds at Demarcation point in 1914 was delayed 

 until the middle of the month of May, owing to more wintry weather and cold 

 nights, and none of the deeper ponds or lakes showed any signs of melting. 

 On May 16 there was only a light snow layer on the tundra, and some of the 

 shallow ponds were quite free of snow or ice, others only partly so, and often 

 communicating with the melting water in the surrounding swamps. Their water 

 had a temperature of 35° F. at 7.30 p.m. (air 29° F.). Then followed several 

 days of colder weather, forming new ice on the melted ponds and snow 

 upon the tundra, which, however, soon meltbd away.^ Besides the dipterous 

 larvae mentioned above a number of other aquatic insects (other diptera, 

 collembola, dytiscids, etc.), snails {Aplexa hypnorum),^ etc., were now 

 found in the ponds. My observations for the period from the end of May to 

 the middle of July, 1914, are in Camden bay (Collinson point and Konganevik). 



On May 26 the tundra was almost impassable owing to soft or melted snow, 

 though the vegetation and invertebrate animal life had not yet progressed much 

 in development, and the rivers were breaking up. On the last day of the 

 month the tundra still looked wintry, and the vegetation was far behind. 

 The deeper ponds were mostly melted, but had ice at their bottoms for long 

 stretches or were partly covered with ice, the latter reaching to the bottom. 

 The overflow from the melted snow assembled in temporary pools and streams, 

 while the higher parts of the tundra still had much snow. There were, however, 

 large, bare stretches, especially nearest the coast. I consider it very possible, 

 that the cold and cloudy weather at the end of May and beginning of June, 1914, 

 delayed the arrival of the spring (summer) that year beyond the normal. 

 The vegetable and animal life of the freshwater ponds, even if these were 

 only partly melted, however, progressed well, as proved by the number of 

 dipterous larvae and imagines, copepods, (Cyclops magnus and C. vicinus) 



» See Plate IV in Vol. Ill, Part K of these reports. 



2 On May 21 the thermometer stuck into the mud of a shallow pond (water about one inch deep) showed 55 .5* F. at 5 p.m. 

 (Air about 35° F.), which indicates how warm the water in these ponds can become even so early in the spring. 

 " See Vol. VIII., Part A, this serie.i of reports. 



