414 SUPPLEMENT. 



former. The top of the spinous processes in the ascending or 

 anterior half of each elevation of the back-bone projected con- 

 siderably backward. In the descending half, on the contrary, 

 they projected forward, so as to appear as if this part of the 

 spine were inverted. The space between the spinous processes 

 was very great, amounting to nearly two thirds of their lon- 

 gitudinal diameter ; a circumstance which contributes very 

 much to the vertical flexibility of the spine, being much 

 greater than it is in the Boa constrictor, one of the most flexi- 

 ble serpents, as represented by Sir Everard Home, in his com- 

 parative anatomy ; or than it is in the Coluber constrictor, 

 which your committee have examined. The two anterior 

 transverse processes are long and sharp, and are received under 

 or pass within the two posterior transverse processes of the 

 preceding vertebra. They diifer in direction according to the 

 place which they occupy. Those in the highest vertebras 

 pass obliquely downwards ; and those in the lowest, obliquely 

 upwards. The posterior transverse processes also grow broader 

 and less oblique as the vertebrae descend. The whole con- 

 nexion 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 arrangement 

 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 difler in length and direction, 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 con- 

 tinually arising from the vertebral processes, or ribs, and in- 

 serted by an aponeurosis into other bones of a similar kind. 

 Below these is a broad thin lateral muscle or congeries of mus- 

 cles, connected to the ribs only. These muscles, according 



