76 DEVELOr.Ml'AT OF THE SKELETON OF THE TUATAIL^. 



EXPLANATION OF i'HK PLATES i. 

 PLATE I 



Sl'ilKNOUON I'UNCTATUS. — VERTEBllAL COLUMN AND ElBS. 



a., aicli (>r the atlas; a., body of atlas (odontoid peg) ; ex., caudal canal; c.v., cartilaginous 

 vertebra; /./., fibrous tissue ; //.«., accessory hypapophysis; i.p., primary intercentrum ; i./^', median 

 intercentrum ; i.p." , chevron-bone ; i.s., secondary intercentrum ; i.sfj., intcrseptal segment ; 

 >«?/., niyclon (spinal cord); ?!.«., neural arch; wc, notochord ; wee., chordal epithelium; nc.s., 

 chordal slicatb ; n.p., intravertebral cliordal plate ; n.p! , intervertebral chordal plate ; w.sy;., neural 

 spine ; oc.c, ocei|)ital condyle ; o.v., osseous vertebra ; r.cd., caudal rib ; r.s., sacral rib ; r.t., trunk 

 rib; s.l., splitting lamina; s.o., skeletogenous sheath; t.a., interarticular tissue; v.c, vesicula 

 centralis. 



Fig. 1. Stage P. Vertebral Column : — Lateral longitudinal section at about the region of 



vertebrae 6-8. X 50. 



Fig. 2. Stuije P. The same : — Median longitudinal section through the region of fig. 1. x 50. 

 Fig. 3. Stage P. The same : — Transverse section through the intervertebral region of caudal 



segments 2-3. x 40. 



Fig. 4. Stage P. The same : — Section through a vertebral region — the 6th segment in front of 



fig. 3. X 40. 



Stage Q. Vertebral Column : — Lateral longitudinal section in the region of vertebrte 



20-23. X 40. 



Stage Q. The same : — Median longitudinal section through vertebrse 20-23. x 40. 



Stage Q. The same: — Longitudinal section (slightly oblique) through caudal vertebrse 



3-6. X 40. 



Fig. 8. Stage Q. The same : — Median longitudinal section through the basi-oceipital and the 



four anterior cervical vertebrse. x 40. 



Fig. 9. Stages. Vertebral Column: — Longitudinal section through the basi-occipital and the 



three anterior cervical vertebrse. x 25. 



Fig. 10. Stage S. The same : — Median longitudinal section through vertebrse 13-15. x 25. 



Fig. 11. Stage S. The same : — Transverse section through the intervertebral region 5-6. x 25. 

 Fig. 12. Stage S. The same : — Ventral aspect of the last presacral to the 9th caudal vertebrse 



showing free caudal ribs. X 5. 



Fig. 13. Stage T. Vertebral Column : — Median longitudinal section through vertebrae 7-10. X 18. 

 Fig. 14. Stage T. The same : — Median longitudinal section through intercentrum 8-9 of fig. 13, 



showing minute structure. x 50. 



Fig. 15. Adult. Vertebral Column : — Median longitudinal section through vertebrae 9-11. x 11. 

 Fig. 16. Adult. The same : — Ventral aspect of the 10th to the 20th vertebrse showing an abnormal 



condition of the intercentra. | nat. size. 



Fig. 17. Adult. The same : — Median longitudinal section at about the region of the 12th caudal 



vertebra. x 5. 



Fig. 18. Adult. The same : — Caudal vertebrae 7-12 from the left side. | nat. size. 



Fig. 19. Adult. The same : — Transverse section through plane a-b of fig. 17. x 11. 



Fig. 20. Adult. The same : — Caudal vertebra 11 from the left side. | nat. size. 



Fig. 21. Adidt. The same : — Caudal vertebrae. | nat. size. 



' In all the Plates, where colouring has been employed, blue indicates hyaline cartilage and ypUow bone, 

 with the exception of PI. I. fig. 13. 



Fig. 



5 



Fig. 



6, 



Fig. 



7 



