OSSEOUS SYSTEM. 75 



here necessary, from the posterior extremities being brought behind 

 the centre of gravity of the body. With this view the superior spi- 

 nous processes are not unfrequently blended together so as to form 

 a continuous ridge, and in the Flamingo, even the second to the fifth 

 dorsal vertebrse are completely fused together, and their transverse 

 and spinous processes have coalesced into a single plate of bone. 

 The bodies relatively to those of the cervical vertebra? are short, 

 and more or less strongly compressed laterally, in the Penguins 

 being quite crest-shaped, while on the contrary they are very broad 

 in the Ostrich. The anterior usually support strong elongated, 

 and, as in Eudytes and other birds, disjoined inferior spinous pro- 

 cesses for the attachment of the recti antici majores muscles. The 

 lumbar vertebrae are anchylosed with the sacrum and pelvis to form 

 a single lumbo-sacral bone. The portions however which belong 

 to the several bodies can be more or less clearly distinguished. 

 The lumbo-sacral bone is mostly composed of from 9 to 10, or even 

 more, as 15 vertebree (many Grallatorial arid several Gallinaceous 

 birds), rarely of 17 (as in the Ostrich), or 19 (Cassowary). The 

 caudal series of vertebra? exhibits slight differences ; the vertebrae 

 are here very moveable and few in number, and have for the most 

 part considerable transverse and superior, as frequently also inferior 

 spinous, processes. They are hollow even to the last, and form the 

 canal for the spinal marrow. The last camdal vertebra is always of 

 a peculiar shape, and has mostly a strong share-shaped spinous pro- 

 cess arising from it, upon which the remigial feathers of the tail are 

 supported. This process is absent however in birds which have a 

 rudimentary tail, as the Struthionida? and Penguins ; on the contrary, 

 in some of the Scansorial birds where the tail serves as an instru- 

 ment of support in the act of climbing, as in the Woodpeckers and 

 Tree-creepers, the body of the last caudal vertebra is very broad, and 

 supports a peculiar flattened and concave plate. 



The number of the Ribs varies in accordance with that of the dor- 

 sal vertebra?. They always articulate by means of a small head with 

 the body of a single vertebra near to its anterior border, and with 

 the corresponding transverse process by their tubercle. Anteriorly 

 there are situated mostly two, rarely, as in the Cassowary, four false 

 ribs, generally small, and running to a point, which do not reach the 

 sternum. The succeeding true ribs are always laterally compressed 

 and very flat, with the exception of the last rib and the one before 

 it ; from about their middle there proceeds a strong and elongated 

 process, which is very seldom moveably united to the rib, as in the 



