570 CHORD AT A. 



across the tooth, we produce a molar not unlike that of 

 some fossil Mastodons, 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 (i) 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 calcaneum. 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. — Elephantidse. — The modem 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 {Elephas primigenins) 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. — Dinotheridae. — In Dmotherium, an elephant-like 

 animal of the Miocene and Pliocene, the lower 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. 



