74 H. G. SIMMONS. [sec. arct. exp. fram 



larger llian the lateral ones, and has somewhat longer petals, which, 

 however, are hardly more than a third part longer than the calyx-lobes. 

 The glanduluse covering resembles that of the var. ttniflora but is 

 feebler. 



Habitually S. * exaratoides shows a considerable resemblance to S. 

 exarata, Vill., and has also been taken for that species. When exa- 

 mining my material, and comparing it with specimens in the Copen- 

 hagen herbarium, I was for a time inclined to refer my plant to the 

 latter species, the more so, as it is also recorded from the Rocky Moun- 

 tains; but upon closer examination, it appeared that the plant which 

 Hooker calls S. exarata could not be identical with the european 

 species. On the other hand, his description applied very well to my 

 Ellesmereland specimens, and in assuming these to belong to the same 

 form as the Rocky Mountains plant, it was easily understood why 

 Hooker (1. c, I, p. 244) could speak of the difficulty of distinguishing 

 5. exarata from S. caespitosa. Afterwards, when I was studying at 

 Kew, I found the identical specimens from the Hookerian herbarium from 

 which Hooker's description must have been made. They were collected 

 by Drummond in the Rocky Mountains, and on the label stands: "S. 

 caespitosa ?? var. florib. minoribus sed vix". The plant was entirely 

 in accord with my Ellesmereland one, as were also some other speci- 

 mens which will be mentioned in the statement about the distribution. In 

 Copenhagen, I also saw european specimens of it, collected in the 

 Western Pyrenees by the elder Blytt, and also one which was probably 

 from Unalaschka. Blytt's plant has a certain interest, not only be- 

 cause it extends the range of the sub-species so far, but also because 

 it helps one to understand what is comprehended in S. mixta, Lapey- 

 rouse, 1. c. It can hardly be doubted, that his figure 20 represents the 

 same plant as Blytt's specimens, but on the other hand the figure 21 

 gives a plant differing in its looser mode of growth, its strongly veined 

 leaves, and the laxer inflorescence. I should think this must be referred 

 to S. exarata. Don, Mon. gen. Saxifr., p. 433, puts S. mixta, Lap. 

 as a synonym under S. exarata, but Engler has kept S. mixta as a 

 separate species, which may perhaps be right, even if it has originally 

 comprehended different plants. It must, /partly at least, have reference 

 to a plant with veined leaves, but the flowers are represented as pink, 

 which does not apply to 5. exarata. I must, however, leave aside what 

 is really meant by S. mixta, Lap. The true S. exarata differs 

 habitually from our plant in its far more slender growth, in its very 



