ANATOMY OF VERTEBRATES. 185 



broadest in the human foetal pelvis is the least and slenderest 

 in that of the Turtle. To comprehend the nature of the Chelo- 

 nian pelvis, the connections and relative positions of its bones 

 must be studied in the entire skeleton. 



The two bones that articulate with the transverse processes 

 of vertebra3 and, extending l haemad ' (downward or forward), 

 combine at the opposite end with the other bones forming the 

 acetabulum, are those alone which show the essential characters 

 of the ilia in air-breathing vertebrates. In the figure of the 

 pelvis of the Turtle viewed from below or from the haemal aspect, 

 fig. 115, that surface of the sacrum is figured to illustrate the 



115 



Pelvis of Chelone (from below). CLX. 



above character of connection. Two stunted pleurapophyses 

 converge from the two centrums, and afford a close ligamentous 

 attachment to the proximal or upper ends of the ilia, , a. These 

 bones are also attached to the contiguous costal plates of the cara- 

 pace, which they support as stout strong pillars. They slightly 

 expand at their acetabular ends, where each unites with two other 

 bones. The bone c descends and meets its fellow at the mid 

 line, as does likewise the bone b: c c being posterior in position 

 answer to the ischia of the human foatus ; b b to the pubics. 

 These are remarkably expanded, and, besides forming an exten- 

 sive symphysis between b, b, each developes a broad angular 

 process or tuberosity which is ligamentously attached to the 

 plastron, forming the foundation for the support of the pillar, a, 

 that underprops the carapace. 



