74 ORGANS OF SUPPORT, 



with a thin, flexible, cartilaginous prolongation. Their head 

 presents a broad, arched, concave surface, to form a secure 

 and free articulation with the rounded, prominent, transverse 

 processes of the vertebrae. The broad and long transverse 

 processes in the coccygeal region of the column, cover a long 

 pelvic cavity in the male, in which the two divisions of the 

 penis are lodged in their retracted state. As the ribs ex- 

 tend along the whole sides of the trunk, from the head to 

 the anus, there are no cervical nor lumbar vertebrae ; and as 

 there are no legs nor pelvis, there is no sacrum. 



The vertebrae are here more numerous than in any other 

 class of animals, so that there is great flexibility of the 

 whole body, and their articulations are remarkably secure 

 from the extent and the number of the articular surfaces 

 between each pair of vertebras. All the processes of these 

 vertebrae are short, to admit of greater freedom of motion, ex- 

 cepting the four articular processes, which are very broad, to 

 give a greater security of attachment ; and hence the quadran- 

 gular or cubical form presented by the vertebrae of serpents,as 

 seen in the front view of those of the boa constrictor) (Fig. 38.) 

 The lower part of the body of each vertebra terminates in 

 a large, oblique, hemispherical convexity (a,) smooth on the 

 surface, and covered with a thin layer -0 



of cartilage. This prominent end of 

 the vertebra is received into a corres- 

 ponding deep, cup-like cavity (b 9 ) with 

 sharp margins, and lined with carti- 

 lage, at the anterior end of the next 

 succeeding vertebra, and this regular 

 ball-and-socket form of articulation is 

 continued through the whole vertebral 

 column. These articulations are se- 

 cured by strong capsular ligaments, 

 and lubricated by a copious secretion 



of synovia. The two anterior, and the two posterior arti- 

 cular processes present broad flat surfaces, extended trans- 

 versely, those of the anterior vertebra passing over those of 

 the next succeeding vertebra, as in other classes. The 

 shortness of the transverse processes (Fig. 38. c, c, c,c,) 

 allows of a greater extent of lateral motion in the column, 

 and, for the same reason, the vertebral foramina for the 



