582 VICTOR E. SHELFORD 
on warm days). Under conditions unsuitable in any one factor, 
few or no eggs are laid. 
5. Geographic distribution. The geographic distribution of 
C. sexguttata is exactly what the general habitat relations would 
lead one to expect. Within fifty miles of Chicago, I have found it 
always associated with the white-oak and red-oak and with a 
single exception also the shag bark hickory. The same is true in 
east Tennessee. Comparing the distribution of the trees, we find 
that the combined extent of the white-oak and hickory represent 
almost exactly the distribution of this species (fig. 19). That is, 
the geographic distribution is the exact function of the local dis- 
tribution (Ruthven, ’07). 
Fig. 19 A combination of the maps of Schimper ’03, and Transeau, 03, showing 
the geographic plant formations of North and northern South America and 
the distribution of Cicindela sexguttata. 
1a, c, d are forests with broad thin leaves. 
la. Dense tropical evergreen forest, rain-forest. 
ic. Dense temperate evergreen forest, temperate rain-forest. 
1d. Deciduous forest. The large black dots in this area represent locality 
records of C. sexguttata; the heaviest dots combined with crosses are placed over 
the centers of states from which it isrecorded. The lines x and y show the relation 
of its distribution to that of two characteristic trees of the deciduous forest. 
The continuous line (x) represents the distribution limits (except along the Atlan- 
tic Coast of the white-oak (Quercus alba) ; the broken line (y) represents the distri- 
bution limits of the shag bark hickory (Hicoria alba), except where its limits are 
coincident with those of the white-oak. The distribution of these is not the 
same as that of the deciduous forest because the map is based on area with more 
than twenty per cent of woodland. In the savanna region (3b) these trees occur 
along the streams as does C. sexguttata. 
2. Coniferous forest (with narrow thick leaves). 
This is mixed with the deciduous forest in the region of the Great Lakes. In 
southern Unites States it does not properly belong to this map because it is 
dependent upon soil rather than climate (p. 600). 
3a. Tropical steppe and savanna. 
3b. Temperate savanna. 
3c. Temperate grassland or steppe. 
4. Evergreen forest with broad thick leaves. 
Sa. Scrub or thorny forest which merges into desert. 
5b. Desert; 3-5 is very arid desert-like steppe. 
Unshaded area in the north is tundra. 
