[Illustration: FIG. 64.–Diagram of the skeleton of _Testudo elephantopus_, after removal of the left half of the carapace. The plastron is roughly indicated by a section through the middle line. _Fe_, Femur, foreshortened; _Fi_, fibula; _H_, humerus; _Il_, ilium; _Is_, ischium; _P.P._, pubis; _R_, radius; _Scap_, scapula; _Tb_, tibia; _u_, ulna; 3, third cervical vertebra; 1, 3, 5, first, third, and fifth fingers; _XIII_, thirteenth (fifth thoracic) vertebra.] The PELVIS is strong. Ilium, pubis, and ischium meet at the acetabulum. The dorsal end of the ilium is generally broadened, and is attached to one or both sacral vertebrae, but it is also in contact with the superimposed last costal plate. This additional connexion often becomes predominant and the sacral vertebrae are partly or completely relieved of the iliac support, fusing in this case more or less with the costal plates. The pubes have strong lateral processes, directed obliquely forwards and downwards. The pubes and the ischia, which latter are much smaller, form broad symphyses, and these are connected with each other by a longitudinal cartilaginous band (_Chelone, Trionyx_); or the connecting bridge is broad and quite ossified (_Testudo_), forming in the latter case two roundish obturator-foramina. Cartilage frequently remains at the anterior end of {320}the pubic symphysis, and a smaller, longer, and narrow piece of cartilage extends sometimes backwards from the ischiadic symphysis, as the so-called hypo-ischium. In the Pleurodira the ends of the ilia, and those of the lateral processes of the pubes, are much broadened and firmly ankylosed with the posterior costal plates and with the xiphiplastron respectively. [Illustration: FIG. 65.–Ventral view of the bony shell of _Chelone mydas_, the Green Turtle, after removal of the plastron (Fig. 66). The costal plates are marked by cross lines to distinguish them from the ribs. _C_, coracoid; _Fe_, femur; _Fi_, fibula; _H_, humerus; _Ma._1-_Ma._12, marginal plates, some of which are fused together; _Nu_, nuchal plate; _PC_, "precoracoid"; _R_, radius; _Sc_, scapula; _I_, _V_, first and fifth digits; _IX_, Ninth vertebra or first thoracic.]