SKELETON OF THE BATRACHIA. 395 



bones is supposed to receive considerable support 

 from their structure and relative position in the 

 skeleton of the frog. The cavity for the lodgement 

 of the brain, which is enclosed by these vertebrae, 

 is perfectly continuous in the same line with the 

 spinal canal, which, indeed, it scarcely exceeds in 

 its diameter. The bones of the face are, at the 

 same time, expanded laterally, so as to bear no 

 proportion to the cranial cavity. The head plays 

 on the vertebral column by two lateral articular 

 surfaces, formed on the root of each leaf of the 

 occipital bone ; w hile its body, or basilar portion, 

 is scarcely connected with the first cervical vertebra, 

 and has no articular surface. 



In place of ribs, we find only small slender 

 detached bones, or rather cartilages, affixed to the 

 extremities of the transverse processes of some of 

 the vertebree : they may be regarded as rudimental 

 ribs.* 



The pelvis consists of two slender and elongated 

 iliac bones, which are extended backwards, and 

 which, at their anterior extremities, merely touch 

 the points of the transverse processes of the last 

 vertebra of the back. This vertebra is much 

 broader than the rest, and although it consists of a 

 single bone only, must be considered as a sacrum. 

 The two pubic and ischiatic bones are exceedingly 

 small, but still contribute to form the acetabulum, 



* The plan of reproduction in these animals requires that the 

 ovary, or organ which contains the eggs, should be capable of 

 enormous dilatation, in order to contain the immense bulk to which 

 these eggs are expanded, previously to their being brought forth. 

 It was probably in order to make room for this dilated ovary that the 

 ribs have not been developed. 



