MORPHOLOGY OF TELEOSTEAN HEAD SKELETON. 591 



Fig. 3. Stage III, — The same of a larva, 6"G mm. long, x 50. 

 Fig. 4. Stage IV. — The same of a larva; IG'O mm. long, x 16. 



Fig. 5. Stage IV. — Dorsal view of the skull with the membrane bones. 

 X 16. 



Fig. 6. Stage I. — Lateral view of the chondro-cranium. x 70. 



Fig. 7. Stage II. — Lateral view of the chondro-cranium. x 60. 



Fig. 8. Stage III. — Lateral view of the chondro-cranium. x 50. 



Fig. 9. Stage IV. — Lateral view of the chondro-cranium. x 16. 



Fig. 10. Stage IV, — Lateral view of the skull with the membrane bones. 

 X 16. 



Fig. 11. Stage IV. — Posterior view of the skull with the membrane bones. 

 X 16. 



Fig, 12, Stage IV, — Ventral view of tiie posterior region of the chondro- 

 cranium. X 16. 



Fig. 1'6. Stage IV. — Internal view of the mandibular and li^'oid arches with 

 tlie mandible removed, x 16. 



Fig. 14. Stage II. — Ventral view of the hyoid and branchial arches, x 60, 



Fig. 15. Stage III. — Ventral view of the hyoid and branchial arches, x 50. 



Fig. 16, Stage IV, — Ventral view of the hyoid and branchial arches, x 16. 



Figs. 17—24 are all of the adult : 



Fig. 17. — Side view of the cranio-facial skeleton. X 3s. 



Fig, 18, — Dorsal view of the cranium, x 32- 



Fig, 19, — Side view of the cranium, x 3^. 



Fig. 20, — Internal view of the cranium, x 3^, 



Fig, 21. — Ventral view of the cranium, x 3i. 



Fig. 22. — Ventral view of the hyoid and branchial arches, x 3|. 



Fig. 23, — External view of the mandibular and hyoid arches with 

 the mandible removed. X 4, 



Fig. 24. — Posterior view of the cranium, x 3^. 

 Fig. 25, — Sagittal section of the intercranial uotochord of a larva, 63 mm. 

 long, X 80, 



Fig. 26, — The same of a young stickleback, 21"0 mm, long, x 80. 

 F'lG, 27. — The same of a full-grown adult, 47'0 mm. long, x 80, 

 Fig. 28, — Transverse section through the labial cartilage of the adult, 

 X 35, 

 Fig. 29. — The same, but 30 sections behind, x 35. 

 Fig. 30. — Transverse section through the pre-elliuioidal and pre-palatine 

 regions of larva belonging to Stage IV. X 140. 



