The Skeleton 



85 



a dorso-laterally projecting crest; medially it is 

 firmly united to the sacral ribs (Fig. 18, 5) while its 

 outer side forms the upper and greater part of the 



Fig. 28. Pelvis and Sacrum of an Alligator (Caiman 

 latirostris). X|. (Brit. Mus.) (After Reynolds.) 



1. ilium. 



2. ischium. 



3. true pubis. 



4. epipubis (so-called pubis). 



5. acetabular foramen. 



6. neural spines of sacral verte-; 



brae. 



7. symphysis ischii. 



8. process bearing prezygapo-1 



physis. 



acetabulum. Its outer and lower border has two 

 surfaces, the larger and more posterior articulating 

 with the ischium, the other with the cartilaginous 

 pubis. 



The ischium (2) is a slightly arched bone, its 

 ventral end a flattened blade articulating with its 

 fellow, its dorsal end enlarged and thickened to 

 articulate with the ilium, pubis, and epipubis. 



