150 FIRST FORMS OF VEGETATION. 
inches thick, which look like ginger-bread, but have 
a very earthy and rather bitter taste. ‘Our com- 
panion,’ says Commander Mayne, ‘gave us this 
food, which the Indians call “ Wheela,” with milk. 
But two or three mouthfuls were all we cared to 
take.’ 
Another beard-like lichen (Usnea florida, Fig. 
12), often growing along with the rock-hair, is 
gathered in great quantities in North America, 
Fic, 12.—USNEA FLORIDA. 
from the pine-forests, and stored up as winter 
fodder for cattle in inclement seasons. Goats, 
and especially deer, are fond of it ; and in winter, 
when other food is scarce, they hardly leave a 
vestige of it on the trees within their reach. The 
tortoises of the small rocky islands of the Galapa- 
gos Archipelago subsist almost entirely upon it. 
In this country it is one of the most picturesque 
ornaments of our pine forests. When fully deve- 
