104 ALLEN’S NATURALIST’S LIBRARY. 
in the interior more to the south. It is curious, remarks 
M. Grandidier, to find races and species of the same genus so 
exactly restricted, that one has only to cross a river, not 
necessarily large, in order to obtain on one bank certain 
species of Propithecus, whereas those occurring on the opposite 
bank may be of a very distinct species or race. To what 
influence in their surroundings can all these variations be 
ascribed? One can understand that species inhabiting a 
wooded and humid country, or living among granitic moun- 
tains (as P. diadema does), would differ in size and fur from 
other members of the same genus which live in dry and arid 
plains (as in the case of P. verreauxi); but how can the great 
variations that occur in members of the same species living 
afew miles, and perhaps only a few metres, apart, be explained, 
when the external conditions are almost the same P 
Habits——The habits of the different species of Sifaka are 
very similar. They live in companies of six or eight, and are 
very gentle and inoffensive animals, wearing always a most 
melancholy expression, and, as a rule, being morose, inactive, 
and more silent than other Lemurs. They rarely live long in 
captivity. In their native state they are most alert in the 
morning and evening, as during the heat of the day they con- 
ceal themselves amid the foliage of the trees. When asleep or 
in repose, the head is dropped on the chest and buried between 
the arms, the tail rolled up on itself and disposed between 
the hind-legs. The Sifakas live exclusively on vegetable sub- 
stances—leaves, fruits and flowers—their diet not being varied, 
as in the other groups, by small birds, eggs, or insects. Their 
life is almost entirely arboreal, for which the muscles of their 
hands and feet, as well as the parachute-like fold of skin 
between their arms and body, and their peculiarly hook-like 
