1176 The “Collar Bone” in the Mammalia. (December, 
very rudimentary in the hares, and in the rabbits existing as a 
bone incomplete at the ends, a condition which we would expect 
to find from the variation in life habits. 
Taking up the large order of “ hoofed” animals, the Ungulata, 
we note the complete absence of the clavicles in all the forms, 
not a vestige of the bony structure being found in any one of 
them. They are the “runners” par excellance, and if we may 
use the expression, ive on their legs, the capacity for speed and 
endurance being one of the chief factors aimed at by natural 
selection in maintaining and perfecting the species. 
Here we find the fore limbs subserving the hind limbs in rela- 
tion to work; the latter are the main motor power in running, 
while the fore limbs act chiefly as supporters and guiders; hence 
the entire absence of clavicles. The marine Mammalia, with their 
rudimentary limbs, have no clavicles. 
In the flesh-eating animals, Carnivora, the clavicles are always 
rudimentary, and in many cases entirely wanting. They are bet- 
ter developed in the cats, Felidz, than in any other family of the 
order (though the articular extremities of the bone are lost), for 
the clutch which follows the spring in securing their prey, brings 
the fore limbs into more active use than in the dogs and wolves, 
Canide, which run their quarry to “ the death,” and then pull it 
down by force of numbers. Many of the cats, too, frequent 
trees, but they spring from place to place and do not properly 
climb. Several species of bears also climb, but the habit is 
more acquired than natural, the fore limbs clasp the trunk while 
the hind ones secure a foothold and, so to speak, shove the ani- 
mal upward, very different from the active movements of a nat- 
ural climber. 
In the bats, Chiroptera, as we would expect from their mode 
of life, the anterior limbs being the main factors in their flight, 
clavicles are rappr long, curved and strong. 
The arboreal Lemurs also have them developed. 
In the order Primates we have the clavicles present in all, from ` 
arboreal monkeys up through the anthropoid apes to man, 
were the anterior limbs attain such perfection, with ball and 
The badger (Taxidea) is a striking exception to the general rule, being an emi- 
F imal yet devoid of clavicles. The fore feet are armed with ex- 
' curved claws, probably bringing greater leverage on the 
l thus pnr mary ementing, the absence of clavicles. 
