bit, and with short
feet provided with claws. In seeking food and avoiding enemies in
different habitats the limbs and feet radiate in four diverse
directions; they either become _fossorial_ or adapted to digging habits,
_natatorial_ or adapted to _amphibious_ and finally to _aquatic_
habits, _cursorial_ or adapted to swift-moving, terrestrial progression,
_arboreal_ or adapted to tree life. Tree life leads, as its final stage,
into

LIMBS AND FEET.
Volant.
/
Fossorial. Arboreal.
\ /
Short-limbed, plantigrade, } Ambulatory
pentadactyl, unguiculate } or
Stem. } Terrestrial.
/ \
Natatorial. Cursorial
Amphibious. Digitigrade.
/ \
Aquatic Unguligrade.

TEETH.
Omnivorous.
{ Grass.
{ Fish. | { Herb.
Carnivorous { Flesh. | Herbivorous { Shrub.
\ { Carrion. | / { Fruit.
\ | / { Root.
\ | /
\ | / Myrmecophagous.
\ | / / Dentition reduced.
\ | / /
\ | / /
\ | / /
\ |/ /
Stem: Insectivorous.

the parachute types of the flying squirrels and phalangers, or into the
true flying types of the bats.... Similarly in the case of the teeth,
insectivorous and omnivorous types appear to be more central and ancient
than either the exclusively carnivorous or herbivorous types. Thus the
extremes of carnivorous adaptation, as in the case of the cats, of
omnivorous adaptation,