64 Nr. 2. C. H. OSTENFELD and C. SYRACH LARSEN: 
L. Gmelini (L. Czekanowskiü, SZAFER), and we find the 
reports of the most easterly occurrence of L. sibirica within 
this belt, where CAJANDER found it on the Lena almost as 
far east as Oleminsk (Act. Soc. Sci. Fen. XXXII, No. 3, 
p. 8). In a southerly direction, it has been collected in the 
forest east of Urga and north of the river Tola (C. W. 
CAMPBELL, 1902, Kew Herb.). In determining the borderline 
towards the south, we have the exhaustive reports of PRINTZ 
(Veget. Sib. Mong. Front. 1921), and the already- 
mentioned observations of PRICE & Simpson for the eastern 
section; but. from this point, where we are without their 
observations in the south of Russian Siberia, and until 
we reach European Russia, special investigations regarding 
the larch are lacking. The most probable boundary is the 
one given here (according to Zon & SPARHAWK: Forest 
Resources of the World, 1923, p. 286), as it undoubtedly 
everywhere constitutes one of the farthest-reaching forest 
outposts. Its occurrence in the Urals has been investigated 
by both Körren and Korsuinsky, and their observations, 
have been followed here. Their statement, that L. sibirica 
is not to be found on the western side of the Urals towards 
the north right up to the source of the Petschora, has, 
nevertheless, been somewhat modified, the boundary having 
been fixed at a rather less northerly point. KöPrpEn also 
mentions a more southerly line than Korsnınsky. The 
boundary line in the southern outposts of the Urals has 
been drawn according to KorsHinsky’s and KOUZNETZOV’S 
maps, which are the most detailed; the two isolated occur- 
rences on the south-east of the Urals are included in the 
general are of distribution. 
In the north of Russia and in Siberia, the West-Siberian 
larch is, as a rule, only a small tree, but along the sides 
