$18 ZOOLOGY. 
Order XII. Primates.—The last and highest order of 
mammals contains a series beginning with creatures resem- 
bling squirrels and bats, 7.¢., the lemurs, and comprising 
monkeys, apes, and ending with man. In all the Primates, 
the legs are exserted almost or quite free from the trunk, 
with the great toe of the hind foot usually enlarged and .op- 
posable to the others ; nails, except in the marmosets, replace 
claws ; the teeth are usually of the following formula : 
2-2 1-1 3-3 38—3 
Toe Tap Pare M53) 
with one aimee ue teeth are always present ; ube pre- 
—3 
3-3" 
The hemispheres of the brain may in the lower forms be 
quite smooth, but in all there is a well-developed ‘“ calcarine 
furrow,” giving rise to a ‘‘ hippocampus minor” within the 
posterior cornu of the ventricle, by which the posterior lobe 
of the cerebrum is traversed (Flower). The collar-bones 
({clavicles) are for the first time in the series well developed. 
The placenta is also different in shape from that of other 
mammals, being disk or cake-like, but in lemurs it is ‘‘ diffuse.” 
The Primates are divided into two sub-orders, ¢. ¢., the 
Prosimie and Anthropoidea. The former group embraces 
the lemurs, which vary in size from that of a rabbit to a 
large monkey. They are covered, the face as well as the rest 
of the body, with a dense fur; walk on all-fours, usually 
‘have long tails, though the lori is tailless, while the fore 
limbs are shorter than the hind limbs. The skull is small, 
flattened, and narrow in front; the brain-cavity. small in 
proportion to the rest of the skull, 7. ¢., the face compared 
~with the monkeys. The cerebral hemispheres are small and 
flattened, the frontal lobes narrow and polntell, and behind 
they only slightly cover the cerebellum.* 
By some authors the lemurs are separated from the Pri- 
mates, the Insectivora and Cheiroptera being placed between 
the Prosimie and the other Primates. They have characters 
in which they resemble Jnsectivora, Rodentia, and Carnivora, 
but the weight of organization, or the sum of their charac- 
ters, ally them nearest to the monkeys. They are therefore 
essentially a generalized or ancestral type. Recent discov- 
* In Hapalemur the single pair of teats are situated on the arm. 
molars are usually y = —. but in the American monkeys © 
