THE FLYING-SQUIRRELS OF ASIA AND AFRICA 239 
tooth-structure obtains in most of the flying-squirrels of 
Europe and Asia, although in the species shown in the 
plate the structure has become somewhat more complicated 
owing to the taller crowns of these teeth. In the scale-tails, 
on the other hand, a totally different type of tooth-structure 
obtains, the crowns of the molars being divided by trans- 
verse folds of enamel, after a fashion recalling that which 
prevails in certain South American rodents. 
To the anatomist these differences are sufficient to render 
it quite certain that the scale-tailed flying-squirrels are, at 
most, but very remotely connected with their non-scaled 
namesakes of the northern hemisphere. The non-scientific 
person might, however, say that the “ yard-arm” in the 
parachute and the scales on the tail are features which 
have been developed concomitantly with the acquisition of 
the parachute itself in certain species of flying-squirrels, 
and that, like the differences in the structure of the teeth, 
they are of no particular importance one way or the other 
in regard to the affinities of the animals in which they 
occur. 
A few years ago it would have been impossible to 
produce absolutely decisive evidence as to the futility of 
such specious arguments. Recently, however, there has 
been discovered on the West Coast of Africa—that home 
of strange and primitive types of animal life—a rodent 
looking not unlike a large dormouse, which is really the 
“grandfather” of all the flying scale-tails. For this creature 
(known as Zenkerella), although without a parachute, has 
scales on its tail like Anomalurus, and teeth of the same 
type as the latter. Whether it is the actual form from 
which the flying scale-tails are descended, or whether it 
is itself a descendant of such ancestral form, may be left 
an open question, as it is one of no practical importance, 
