536 



ZOOLOGY 



SECT. 



radius and ulna are ankylosed at their extremities. The carpus 

 has seven bones in the Manatee : the pisiform is absent. In the 

 Dugong coalescence takes place between the carpal bones, so that 

 the number of ossifications is reduced in the adult. There are 

 five digits, all of which possess the normal number of phalanges. 



The pelvis is represented by a pair or more of vestiges widely 

 separated from the spinal column, and having a vertical position : 

 they probably represent the ilia. 



Skeleton of the Ungulata. — In general, the centra of the 

 Ungulata are more or less distinctly opisthocoelous. The odontoid 

 process of the axis (Fig. 1153) has a peculiar spout-like form in the 

 majority of the Ruminants, and in a less marked degree in the 



od 



od 



trans 



y-F^3 



Fig. 1153. — Axis of Red Deer (Cerviis elaphus). A, lateral view ; B, dorsal view. ep. epiphysis 

 of centrum ; od, odontoid process ; jji. s. post-zygapopliysis ; sp. neural spine ; trans, trans- 

 verse process. 



Horses and Tapirs : in the Chevrotains, the Pigs and the Pro- 

 boscidea it is conical. In the Ruminants the cervical vertebrae 

 present a median keel below, produced in the posterior part of the 

 region into a process. The development of the cervical neural 

 spines varies : in most they are elongated and compressed ; but in 

 the Horses they are almost completely absent, and in the Elephants 

 they are all small, with the exception of the last. The number 

 of thoraco-lumbar vertebrae is nearly always nineteen in the 

 Artiodactyles, twenty-three in the Perissodactyles and in the 

 Proboscidea. Hyrax has a larger number of trunk-vertebrae — 

 twenty-eight to thirty — than any other terrestrial Mammal. The 

 transverse processes of the lumbar vertebrae are nearly always 

 elongated, flattened, and directed outwards, or outwards and slightly 

 forwards. Usually there is a single wide sacral vertebra united 

 with the ilia, ankylosed with which behind are a varying number 



