720 



COMPARATIVE ANATOMY 



Neural Ptate 



Costal 

 Shield 



Bpiderm 



Cutis. 



Fig. 425. 



A. Diagrammatic transverse section through the shell of Testudo. The horny 

 shields have been removed from the right side. On the left side one can see the 

 neural, costal, marginal, and pectoral shields. The bony dermal plates are dotted. 

 Cap, capitular portion of rib ; Sp.C, position of spinal cord. B, Vertical section 

 through part of the shell, magnified and diagrammatic. B, Bony layer of cutis ; 

 L, leathery layer of the cutis ; M, cells of the Malpighian layer ; P, star-shaped 

 pigment-cells ; Sc, stratum corneum composing the horny shields. C. Diagram of 

 skeleton of Testudo elephantopus, after removal of the left half of the carapace. 

 The plastron is indicated by a section through the middle line. Fe, femur, fore- 

 shortened ; Fi, fibula ; H, humerus ; II, 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. (After Gadow). 



are mostly fused. There are three or four pre-caudal vertebrae with 

 terminal pygostyle (Fig. 418), two cervical, and three to nine thoracic 

 ribs, the latter attached to the sternum. The pectoral girdle is made up 

 of paired, blade-like scapulae, paired coracoids which unite with the 

 sternum, and three clavicles fused in the middle to form the "wishbone" 

 or furcula. The pelvic girdle is a solid bone, composed of the fused 

 ischia, ilia, and pubes. The pelvis is firmly fused with the sacral verte- 

 brae. The leg skeleton consists of a large femur, a slender fibula, and a 

 long, stout tibiotarsus, made up of the fused tibia and proximal tarsal 

 bones; the ankle joint is between the tibio-tarsus and the tarso-meta- 

 tarsus. 



The foot has four digits, the hallux usually being directed backward. 



