THE RABBIT. 



71 



them, and these are commonly counted as sacral vertebrae 

 also (fig. 41, p. 75). The first true sacral has a very broad 

 centrum, from which the greatly expanded transverse pro- 

 cesses project, ending in a flattened surface joined im- , 

 movably to the pelvic girdle. The remaining vertebrae 

 narrow rapidly backwards; when fused (in the adult 

 rabbit) their limits can be distinguished by the nerve- 

 notches (converted into holes by the fusion) which are on 

 the ventral side. 



8. The Caudal Vertebrae are small, and about sixteen 

 in number. As they are traced back they show a gradual 

 change zygapophyses and transverse processes disappear, 

 then the neural arch becomes incomplete dorsally, and 

 presently is lost altogether, the final vertebrae consisting of 

 centrum only, and looking not unlike finger-joints. 



9. Limbs and Limb-girdles. The bones within the 

 body which give support to the limbs are called the limb- 

 girdles a slightly misleading term, because they do not 

 completely encircle the body, but only partially so. Limb- 

 girdles and limbs are constructed on one general plan 

 throughout the air-breathing vertebrates (as distinguished 

 from the fishes) ; but the plan is very variously modified to 

 meet the requirements 

 of running, jumping, 

 burrowing and the 

 multitudinous other 

 modes of utilizing the 

 limbs. A diagram of 

 this general plan is 

 given in fig. 35. The ^'~ 

 girdle is two-thirds of 

 an oval hoop, and each 

 half is divided by the 

 point of articulation of 

 the limb into a dorso- 

 lateral and ventral portion. This ventral portion is a fiat 

 plate again divided by a large perforation (paired) into an 

 antero- ventral and postero-ventral portion (fig. 36). To 



VEHTCBfiAL 



Fig. 85. END VIEW OF IDEAL GIRDLE 

 AND LIMBS. 



