570 CHORDATA. 
across the tooth, we produce a molar not unlike that of 
some fossil Aastodons. The ridges are then filled up by 
the addition of cement, and further deepening of the valleys 
and multiplication of the ridges would produce the tooth of 
the elephant. The worn surface presents crests of enamel, 
between which are alternate layers of dentine and cement. 
It should be specially noted that the elephant’s molar is 
produced from the simple brachydont multitubercular type 
by a similar and parallel series of processes to those in the 
ox and horse, consisting of (1) multiplication of enamel 
crests ; (2) heightening of the tooth to allow for wear; (3) 
addition of cement. 
The limbs in elephants show primitive characters. 
Although the clavicles are lost and the femur has no third 
trochanter, the radius and ulna are quite distinct and per- 
manently crossed and the fibula is well formed, articulating 
with the caleaneum. The animal is practically plantigrade 
and moves slowly; the carpus and tarsus are not twisted 
nor interlocked to form alternate rows, but are serial. Each 
toe has a small broad hoof, the weight of the body being 
borne on the sole or pad of the foot. Elephants are strictly 
herbivorous, feeding principally on the leaves of trees, such 
as the mimosa. Their stomach is simple and there is a 
large caecum. : 
Family I.—Elephantidz.—The modern elephants are found in the 
Oriental and Ethiopian regions. The molars of the African Elephant 
have diamond-shaped ridges, the ears are larger and both sexes have 
tusks. The Mammoth (Ziephas primigentus) flourished in recent 
times in Europe, N. Asia and parts of America. It had a woolly 
coat, enormous curved tusks and broad deep molars. Other fossil 
elephants of the Pliocene and Pleistocene connect modern elephants 
with the mastodons. These had large straight tusks and in some the 
molars were tubercular. In many there was a small pair of lower incisors. 
Mastodons first occur in the middle Miocene and extend throughout 
Pliocene in Europe and into the Pleistocene in N. America. They 
are important, as they clearly show us the lines along which the 
elephants have been evolved from a primitive ungulate stock. 
Family II.—Dinotheridz.—In Dénotherium, an elephant-like 
animal of the Miocene and Pliocene, the /ower incisors hung down- 
wards below the chin as a pair of long tusks. The molars were 
bilophodont or trilophodont and had no horizontal, but a regular 
vertical, succession. 
