23 
Low-arctic: this subdivision includes the islands of the 
Canadian Arctic Archipelago (with the above exceptions) north 
to the southern parts of Devon, Cornwallis, Bathurst, and Melville 
islands, and warmer microthermal areas along the east and west 
coasts of Ellesmereland. It is taken to include those areas north 
of the high-subarctic subdivision that lie south of or are in north- 
ern outliers of the 40°F. (4.4°C.) July isotherm shown in Figure 
11 of Rae (1951) and Figure 3 of Porsild (1955); Greenland for 
varying distances north of latitude 70°N., but rarely north of 
latitude 76°N. 
High-arctic: areas north of the low-arctic subdivision or 
not isolated by outlying 4Q°F. isotherms. 
In some doubtful cases, the northern limit in Eurasia has 
served as a basis for assigning certain circumpolar species to the 
subdivision considered most suitable, but it must be emphasized 
that this classification cannot be resolved into a purely mechan- 
ical sorting out of plant ranges according to the above bound- 
aries. The general pattern of distribution of each species must 
be borne in mind, as well as the distribution of local micro- 
climates. 
The distribution in North America and Greenland of all 
the high-arctic and low-arctic plants listed has been mapped by 
Porsild (1957), who has also done the same for many of the 
hi gh-suba retie species. Many of the species have also been 
mapped for North America and Greenland by Raup (1947). The 
world distribution of the amphi-Atlantic species (plants with 
their main areas on both sides of the Atlantic Ocean) has been 
mapped by Hulten (1958), with the exception of the doubtfully 
amphi-Atlantic Polygonum boreale (Lange) Small. References 
to maps of many of the low-subarctic species, as well as to 
those of the other subdivisions, are given by Scoggan (1957). 
Previous publications referring to the flora and vegetation of 
Churchill are as follows: Beckett (1945); Bell (1880); Gardner 
(1937); Gillet (1948); Grontved (1936); Giissow (1933); Johansen 
(1933); Macoun (1911); Rae (1850); Ritchie (1956; 1957); Scoggan 
(1957); Stumer (1933); Tyrrell (1897). Thomson (1953) has listed 
the lichen flora of the area. (The following publications refer to 
the animal life of the area: Taverner and Sutton (1934); Beckett 
