POLYPROTODONTS 
front of the fore limbs, a trace of the primitive lateral 
membrane being left in what is called in those animals 
the metapatagium. There is a kind of a hint that 
in the earliest known bird, Archaeopteryx, a lateral 
feathered membrane existed besides the special patagium 
with its feathers in front of the fore limb. A remarkable 
fact about these small flying phalangers is that the 
power of flight appears to have been independently 
produced more than once in the group. For we find 
several types of them each of which is separately re- 
lated to a non-flying form; we suppose, therefore, 
that each has been evolved separately. The same 
conclusion can be come to with regard to the flying 
squirrels, real squirrels that is to say, for the marsupials 
which we are now considering are sometimes termed 
flying squirrels. In Sciuropterus and Anomalurus, of 
which the former is often to be seen at the Zoo, we 
have parachuted squirrels not nearly akin to each 
other, and therefore possibly to be derived from different 
forms of merely arboreal squirrels. The carnivorous 
polyprotodont marsupials have not as yet produced 
any flying forms. 
THE TASMANIAN WOLF OR JHYLACINE 
This wolf-like creature is not a wolf but a repre- 
sentative of the polyprotodont section of the marsupials, 
called polyprotodont because the lower incisors are 
numerous instead of reduced to two as in the vegetable- 
feeding diprotodonts. The thylacine and its polypro- 
todont allies show another feature, not found in any 
other mammals, except the whales, and that is that the 
total number of the teeth exceed the normal forty-four. 
This is the original number of teeth, as it appears, in 
the higher mammals, as testified to by various extinct 
forms; from this perfection of tooth numbers most 
living mammals have degenerated. Another feature 
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