Tundra formation. — Marine Algal Formation. 349 
conditions are unusually severe the vegetation forms a scant covering to the 
stony earth the socalled Rock tundra. Level depressions in the tundra which 
collect the melted snow water areswampy places like moors where a scanty 
turf consists of sphagnum with small phanerogamic species Empetrum nigrum, 
Ledum groenlandicum (= L. latifolium), Betula glandulosa, B. nana, Me- 
nyanthes trifoliata, while on gravelly ridges in the Hudson Bay region grow 
Salix anglorum, S. phylicifolia, none of them exceeding a few inches in height. 
b) Marine Algal Formation. 
“A thorough study of the distribution of the marine Algae of the Arctic 
Sea has led KJELLMAN to the position that the marine vegetation of Baffın 
Bay to which the flora of the Canadian Arctic Sea seems to approach nearly 
is extremely isolated. It possesses a considerable number of elements wanting 
in the rest of the arctic flora; its characteristic species are partly different and 
one of them belongs to a generic type that is not represented at all in the 
floras of the other arctic marine phytogeographic provinces. The character of 
the marine vegetation in the American province is chiefly marked by Fucus 
vesiculosus, Agarum Turneri, Laminaria longtcruris, L. atrofulva, L. cuneifolia, 
Alaria. 
Within the American province according to KJELLMAN’') the following species 
may be regarded as the most abundant ones: 
Lithothamnion glaciale Kjellm. Chorda filum L. 
» polymorphum L. Desmarestia aculeata L. 
Polysiphonia urceolata Lightf. Dichloria viridis Mull. 
Rhodophyllis dichotoma Lepech. Dictyosiphon foeniculaceus Huds. 
Rhodomenia pertusa Post et Rupr. Enteromorpha compressa L. 
» palmata L. Monostroma fuscum Post et Rupr. 
Ptilota pectinata Gunn. » Biyttii Aresch. 
» plumosa L. Diplonema percursum Ag. 
Diploderma miniatum Ag. Spongomorpha arcta Dillw. 
Fucus vesiculosus L. Cladophora rupestris L. 
»  Sfiliformis Gmel. Rhizoclonium pachydermum Kjellm. 
Agarum Turneri Post et Rupr. Chaetomorpha Wormskioldii Fl, Dan. 
Laminaria longicruris De la Pyl. » melagonium Web et 
» atrofulva J. G. Ag. Urospora penicilliformis Roth. [Mohr. 
» cuneifolia J. G. Ag. Rivularia hemisphaerica L. 
c) Formations of the Pribilof islands. 
The Pribilof group of Islands (St. Paul, St. George and two islets) is about 
350 kilometers (220 miles) north of the Aleutian chain and is of volcanic origin. 
The highest land is on St. George where a precipitous cliff fronting the sea 
ıt) The Algae of the Arctic Sea. Kongl. Svenska Vetenskaps-Akademiens Handlingar Bandet 20, 
No. 5. Stockholm 1883: 78, 
