OF REFTXLFS. 
311 
amounting to nearly two thirds of their longitudinal di- 
ameter; a circumstance which contributes very much to 
the virtical flexibility of the spine, being much greater 
than it is in the Boa constrictor, one of the most flexible 
serpents, as represented by Sir Everand Home in his 
comparative anatomy; or than it is in the Coluber corn 
strictor, which your committe have examined. The 
two anterior transverse processes are long and sharp, and 
are received under or pass within the two posterior trans- 
verse processes of the preceding vertebrae. They differ 
in direction according to the place which they occupy. 
Those in the highest vertebrae pass obliquely downwards, 
and those in the lowest, obliquely upwards. The pos- 
terior transverse processes also grow broader and less 
oblique as the vertebrae descend. The whole connexion 
and proportion of the processes is such, that the greatest 
downward flexion takes place at the top of the curve, and 
'the greatest upward flexion at the bottom; an arrange- 
ment admirably adapted to increase the power of the 
muscles which act in the vertical flexion of the spine. 
The ribs are articulated by a double cavity to a small 
double headed process under the anterior transverse 
process of each vertebra. They differ in length and di- 
rection, those at the bottom of the curve being shorter 
and more spreading than those at the top, so that the 
lower extremities of the whole fall in a right line. 
Muscles . — The principal muscles on the outside of the 
trunk consist of three strong dorsal muscles with oblique 
fibres continually arising from the vertebral processes, or 
ribs, and inserted by an aponeurosis into other bones of a 
similar kind. Below, there is a broad thin lateral muscle 
or congeries of muscles, connected to the ribs only. 
These muscles according to their situation act in per- 
forming the various inflexions of the body. 
On the inside of the ribs a series of their muscles was 
observed, arising from the bodies of the vertebrae, pass- 
ing obliquely downwards and forward under the ribs and 
over the fourth, and afterwards inserted into ribs beyond. 
These muscles in conjunction with others, according to 
