378 Morten P. Porsild 



as an albino-form. Sometimes they are seen growing together, as at 

 a delta formed by a mountain stream which discharged into a lake 

 at the head of Amitsuarsuk. There no intermediate forms occurred; 

 on the contrary it appeared as if they were hereditarily constant, 

 each form having grouped itself around its own streamlet. These 

 streamlets meandered into and across each other, giving the ground 

 the appearance of a plaiting of strips of red and white S. rivnlaris. 



110. Saxifraga groenlandica L. — Very common, and varies 

 considerably everywhere. 



Rosaceae. 



111. Potent ill a i)ulchella R. Br. — On clayey sea-margins 

 at Tartusaq; rare. On gravelly moraine material along the coast at 

 Igdlorssuit; common. 



112. Pot en til la nivea L. sensu ampl. — On heaths and espe- 

 cially on rocks and between stones on moraine material; common. 



This species varies considerably according to the nature of the 

 habitat, hi favourable localities such as rock-ledges with sufficient 

 sunlight, moisture and manure, large vigorous forms occur, with 

 quinate rosette-leaves which appear to agree with var. pentaphijlla 

 Turez. as defined by the newest monographer of the genus Тн. 

 Wolf, hi more wind-exposed places, which are less snow-covered 

 during winter, the plants are lower in growth, more densely felted, 

 and purer white in colour; the rosette-leaves are always ternate and 

 deeply indented, corresponding with the var. pinnatifida Lehm., in 

 Wolf's sense. 



113. Potentilla Va h lia ne Lehm. — Tartusaq, Igdlorsuit, 

 Schade's Islands, in all three places on basalt-gravel. It has not 

 been observed in the gneiss district or in other places on the basalt, 

 but it is probable that it has been overlooked sometimes, as the 

 species when we investigated the district had already finished flower- 

 ing long before. 



114. Potentilla emarginata Pursh. — Amitsuarsuk: Found 

 only on the basalt from a height of about 300 metres above sea- 

 level and upwards ; Schade's Islands : ver}^ common. 



115. Sib bal dia procumbens L. — On damp sunny slopes. 

 Tartusaq, 71° 25': sparingly; Sarfarsuit, 71° 42': in one single locality, 

 but there abundantly. 



This species has not been recorded from the southern part of 

 the Umanaq district by Vahl or Vanhøffen; on the other hand, it 

 has previously been found on the southern coast of Hare Island, 

 70° 20' (PoRSiLD, Hare Island, p. 266) and at Majorqarsuaitsiaq on the 



