Plate XLI. 

 Nyctosaurus gracilis. 



Fig. I. Dorsal vertebrae, ribs, and pelvis; about three-fifths natural size, 

 r, ribs; dv, lumbar or false sacral; s, sacrum; ip, ischio-pubis; ob, obturator for- 

 amen; il, ilium; ftp, prepubes. 



Fig. 2. Abdominal ribs. About three-fifths natural size. 



Fig. 3. Atlanto-axis, from the side. Twice natural size. 



Fig. 4. The same from behind, partly restored. 



Fig. 5. The same, from in front: a, atlantal neurapophysis; ac, axial cen- 

 trum; at, atlantal intercentrum; axi, axial intercentrum; ^,ball of axis; o, odontoid; 

 ftz, postzygapophysis. 



Fig. 6. Hyoid bone. Three times natural size. 



Fig. 7. Extremity a of Fig. 6, more enlarged, from the side. 



