MAMMALIA. 541 
of the fore-limb, Flower and Lyddeker remark : “ The fore- 
limbs are thus brought opposite the sides of the neck, and 
from this position a three-fold advantage is derived: in the 
first place, as this is the narrowest part of the body, they 
add but little to the general width, which, if increased, would 
lessen the power of movement in a confined space ; secondly, 
this position allows of a longer fore-limb than would other- 
wise be possible and so increases its power; and, thirdly, 
although the entire limb is relatively very short, its anterior 
position enables the animal, when burrowing, to thrust the 
claws so far forward as to be in a line with the end of the 
muzzle, the importance of which is evident. Posteriorly the 
hind-limbs are similarly removed out of the way by approxi- 
mation of the hip-joints to the centre of the body.” The 
pelvis is bent inwards towards the middle line in the 
acetabular region and there is no pelvic symphysis. 
The hind-limbs are not so abnormal as the fore-limbs, 
burrowing being effected only by the latter. The lower half 
of the fibula is fused with the tibia. There are five clawed 
toes and the animal is plantigrade. 
We may notice that the mole is a type not only extremely 
specialised for one habitat, but, like the sloth, it has certain 
primitive characters which have persisted from early times. 
We already mentioned that the more primitive types have, 
as a rule, survived in arboreal or fossorial habitats: in the 
mole we recognise primitive characters in the form and 
number of the teeth, in the “‘intercentra,” the episternum 
and possibly the prepollex. 
FossoRIAL ADAPTATION. 
The fossorial type is fo be derived directly from the primitive 
terrestrial and like the others is found in varying degrees. We may 
take the following as examples :—Zchzdna, badger, anteater, armadillo, 
aard-vark, rabbit, bandicoot, marmot, prairie-dog, mole. 
As in the other types, we may take three groups :— 
1. Incidental group: Zchidua, anteater, Prote/es, banded ant- 
eater (Myrmecobius). This consists of animals which prey upon 
earth-loving insects, such as ants. The limbs show strong claws on each 
digit, and in most cases the tongue and salivary gland are modified for 
ingestion of ants, or at least the teeth show an approximation to the 
insectivorous type or a degeneration from a carnivorous type (Proteles ). 
They are really little modified from the primitive terrestrial group. 
