26 



THE BONES. 



second vertebras incline slightly backward ; in the third they are more up- 

 right ; and in the succeeding ones are directed a little forward. In the last 



two they are remarkable for their 

 thickness ; in the fifth an oval-shaped 

 articular facet is observed on their 

 posterior border ; in the sixth, two 

 are present — one in front, correspond- 

 ing to the preceding, and one behind, 

 slightly concave, meeting a similar 

 f;icet on the sacrum. The fourth and 

 iifth vertebrae very often correspond, 

 at their transverse processes, by 

 means of analogous facets.' 



In the Ass, and sometimes in the 

 Mule, only five lumbar vertebrse are 

 found. According to M. Sanson, this 

 is the natural number in the Arab 

 Horse.^ 



4. Sacrum. 



The sacrum results, as already 

 stated, from the consolidation of 

 five vertebrse. This single bone 

 articulates, in front, with the last 

 UPPER S0EFAOE OF LMBAE VERTEBRA. i^^^j^p Vertebra ; behind, with th« 



^\^,'I'^'^lVn?nP'°°"' ^<J"T P V' ^°'!™' first coccygeal bone, and on the 



articular processes; 3, 3, Posterior articu- . -, ■,^^^ ■ ■ -r 



lar processes, 4, 4, Transverse processes. Sides with the ossa mnommata. It 



is triangular, flattened above and 

 ,f'g' 16. below, and from before to behind 



describes a slight curve up- 

 wards. It offers for study a 

 superior and an inferior face, 

 two borders, a base, a summit, 

 and a central canal, the exten 

 eion of the spinal canal. 



Faces. — The superior face 

 presents, on its middle, the spi- 

 nous processes of the sacral 

 vertebrse, which together con- 

 stitute what is called the sacral 

 or supersacral spine. These 

 processes are united at their 

 base only, and remain isolated 

 for the remainder of their ex- 

 tent ; they all incline backwards 



LUMBAR VERTEBRA ; FRONT VIEW. 



, Body ; 2, Its articular face ; 3, Superior spinous 

 process ; 4, Spinai foramen ; 5, Anterior articular 

 processes; 6, 6, Transverse, or costiform pro- 

 cesses , 7, Posterior articular process. 



■We possess the skeleton of a horse which has seven lumbar veriebra3, with the 

 normal complement m the other regions. The seventh is no doubt the first sacTa as it 

 ha^all Its cliaracters. The fifth sacral vertebra is evidently derive^-om tlfecoccygeal 



,•« L ^J»r+ "*"*1""^°V' ^'''™'''J """*="*• ^*^- ^'^"=<'" I^a^ established the fact that there 

 IS m reality no Arab horse ; and asserts that the specific type with five lumbar ve. teC 

 IS very probably of African or.gin, and that these vertebrae, independently of thei, numW 

 ^^TchtasliT '■^'^'^^^'^'■^^*^^^ '^'^'^'^''^ f™« tl^o^e observed in the vertebraTof theXpe 



