THE OSTEOLOGY OF THE REPTILES 



AA. Cartilage Bones, Endoskeletal 



1. Notochordal vertebrae; two or three cervicals, about twenty-three pre- 



sacral; one sacral; moderately long tail; proatlas; atlas embolomer- 

 ous; all vertebrae to tenth or twelfth caudal with free, holocephalous 

 ribs, articulating continuously with intercentrum and diapophysis. 



2. Intercentra between all vertebrae. 



3. Slender and numerous parasternal ribs. 



4. Scapular girdle composed of paired scapulae, procoracoids and meta- 



coracoids, fused in adult life, the three forming the glenoid socket; 

 a supracoracoid and a supraglenoid foramen. 



5. No sternum. 1 



6. Pelvis plate-like with small obturator foramen only; acetabulum 



formed by the three bones, closed. 



7. Legs short and stout. 



8. Humerus dilated at extremities, with entepicondylar foramen. 



9. Carpus with four bones in proximal row; two (three?) in middle row; 



five in distal row ; all well ossified. 



10. Hand pentadactylate, the fourth finger strongest and longest; phalan- 



geal formula 2, 3, 4, 5, 3. 



1 1 . Tarsus composed of nine bones : two in first row ^ ; two in second ; five in 



distal row; all well ossified. 



12. Feet pentadactylate, the fourth toe strongest and longest; phalangeal 



formula 2, 3, 4, 5, 4. 



^ [But see footnote i, on page 122 below. — Ed.] 

 ^ [But see footnote on page 187 below. — Ed.] 



