XI ZOOLOGY 251 



species on another species of beech in Cliile ; and Dr. Hooker 



informs me that just lately a third species has been discovered 



on a third species of beech in Van Diemen's Land. How 



singular is this relationship between 



parasitical fungi and the trees on which 



they grow, in distant parts of the world ! 



In Tierra del Fuego the fungus in its 



tough and mature state is collected in 



large quantities by the women and 



children, and is eaten uncooked. It has 



a mucilaginous, slightly sweet taste, with 



a faint smell like that of a mushroom. cyttaria darwinh. 



With the exception of a few berries, chiefly of a dwarf arbutus, 



the natives eat no vegetable food besides this fungus. In New 



Zealand, before the introduction of the potato, the roots of the 



fern were largely consumed ; at the present time, I believe, 



Tierra del Fuego is the only country in the world where a 



cryptogamic plant affords a staple article of food. 



The zoology of Tierra del Fuego, as might have been ex- 

 pected from the nature of its climate and vegetation, is very 

 poor. Of mammalia, besides whales and seals, there is one 

 bat, a kind of mouse (Reithrodon chinchilloides), two true mice, 

 a ctenomys allied to or identical with the tucutuco, two foxes 

 (Canis Magellanicus and C. Azarae), a sea-otter, the guanaco, 

 and a deer. Most of these animals inhabit only the drier 

 eastern parts of the country ; and the deer has never been seen 

 south of the Strait of Magellan. Observing the general corre- 

 spondence of the cliffs of soft sandstone, mud, and shingle, 

 on the opposite sides of the Strait, and on some intervening 

 islands, one is strongly tempted to believe that the land was 

 once joined, and thus allowed animals so delicate and helpless 

 as the tucutuco and Reithrodon to pass over. The correspond- 

 ence of the cliffs is far from proving any junction ; because 

 such cliffs generally are formed by the intersection of sloping 

 deposits, which, before the elevation of the land, had been 

 accumulated near the then existing shores. It is, however, a 

 remarkable coincidence, that in the two large islands cut off 

 by the Beagle Channel from the rest of Tierra del Fuego, one 

 has cliffs composed of matter that may be called stratified 

 alluvium, which front similar ones on the opposite side of the 



