361 
their articulations ; and thirdly, by the peculiar mobility and 
connection of the ribs. 
''^^umerous as are the vertebrae of the eel, the spine of which 
consists of above a hundred, that of a serpent is in general formed 
of a still greater number. In the rattle-snake [Grotalus homdus), 
there are about two hundred ; and above three hundred have 
been counted in tlie spine of the C oliibcrnatrix. These vertebrae 
are all united by ball-and-socket joints, as in the adult hatracliia ; 
the posterior rounded eminence of each vertebra being received 
into the anterior surface of the next. While provision has thus 
been made for extent of motion, extraordinary care has at the 
same time been bestowed upon the security of the joints. Thus 
we find them effectually protected from dislocation by the 
locking in above and below of the articular processes, and by 
the close investment of the capsular ligaments. The direction 
of the surfaces of these processes, and the shape and length 
n 
VERTEBRyK OF SNAKE. 
of the spinous processes, are such as to allow of free lateral 
ilexion, but to limit the vertical and longitudinal motions ; and 
whatever degree of freedom of motion may exist between the 
adjoining vertebra, that motion being multiplied along the 
column, the flexibility of the whole becomes very great, and 
admits of its assuming every degree and variety of curvature. 
The presence of a sternum, restraining the motions of the ribs, 
would have impeded all these movements, and would have also 
been an insurmountable bar to the dilatation of the stomach, 
which is rendered necessary by the habit of the serpent of 
gorging its prey entire." 
In the Museum of the Eoyal College of Surgeons, Lincoln's 
Inn Fields, is a very fine skeleton of the tiger boa, in which the 
above ball-and-socket apparatus (3an be examined. It measures 
eleven feet two inches, and has no less than two hundred and 
