434 



ZOOLOGY 



SECT 



arm is almost completely hidden by the skin, being applied closely 

 against the side of the body. The manus is provided with five 

 digits, each terminating in a horny claw. The thigh is also almost 

 hidden by the skin ; the pes has four digits only, all provided with 

 claws. 



Skeleton. The spinal column of the Rabbit is divisible, like 

 that of the Pigeon and the Lizard, into five regions the cervical, 

 the thoracic, the lumbar, the sacral, and the caudal. In the cervical 

 region there are seven vertebrae ; in the thoracic twelve, or some- 

 times thirteen, in the lumbar seven, or sometimes six, in the sacral 

 four, and in the caudal about fifteen. 



The centra of the vertebrae in a young Rabbit consist of three 

 parts a middle part which is the thickest, and two thin discs of 

 bone the epiphyses anterior and posterior, applied respectively 

 to the anterior and posterior faces of the middle part or centrum 

 proper. Between successive centra in an unmacerated skeleton 

 are thin disc-like plates of fibro-cartilage the inter-vertebral discs. 



The transverse processes of all the cervical vertebrae, except the 

 seventh or last, are perforated by a canal, the vertebrarterial canal, 

 for the passage of the vertebral artery. The first vertebra or atlas 

 (Fig. 1092, A) resembles the corresponding Vertebra of the Pigeon 

 in being of the shape of a ring without any solid centrum like that 



met 



cent 



FIG. 1092. Lepus cuniculus. A, atlas and axis, ventral aspect, od. odontoid process o 

 axis. B, lateral view of axis. art. articular facet for atlas ; od. odontoid process ; pt. zy 

 post-zygapophysis ; sp. neural spine. C, thoracic vertebrae, lateral view. cent, centrum 

 fac. facet for rib ; met. metapophysis ; pr.zy. pre-zygapophysis ; pt. zy. post-zygapophysis 

 rb. rib ; sp. spinous process. 



of the rest. On the anterior face of its lateral portions are two 

 concave articular surfaces for the two condyles of the skull. The 

 second vertebra or axis (A and B) bears on the anterior face of its 

 centrum a peg-like process the odontoid process (od.) which fits 

 into the ventral part of the ring of the atlas : it has a compressed 

 spine (sp.), produced in the antero-posterior direction ; its transverse 

 processes are short and perforated by a canal for the vertebral 

 artery. All the cervical vertebrae except the last have their trans- 

 verse processes bifurcated into dorsal and ventral lamellae. The 

 seventh differs from the others in having a more elongated neural 

 spine, in having its transverse processes simple and without perfora- 



