282 J^^SH. 



EXPLANATION OF PLATE XIV. 



Fig. II. A sagittal section, showing the division of the peduncle into a dorsal 

 and ventral branch in the diencephal. The relation of Meynert's bundle and the 

 postcommissure are well shown. X 20. 



Fig. 12. Shows the relations of the callosal fibers to those of the supracom- 

 missure, and the apparent separation of the rhinocoele from the paraccEle by the 

 lateral bulging of the callosal eminence. X 20. 



Fig. 13. Shows the thickening of the caudal wall of the infundibulum and the 

 preoptic recess. X 20. 



Fig. 14. A section near the median line, showing the relation of the plexuses 

 to the cavities. X 20. 



Figs. 15-16. Show the direction of the two fiber tracts of the cerebellum. 

 Fig. 1 5 is more dorsal, and shows a single bundle. X 20. 



Fig. 17. A transection through the rhinencephal at the attachment of the 

 olfactory nerves. X 40. 



Fig. 18. A transection through the body of a 17-mm. larva to show the incom 

 plete filling up of the spinal canal by the myel, and the relation of the ligamentum 

 dentatum to the dorsal and ventral roots, and its peripheral attachment. 



Fig. 19. Transection through the myel. X 190. 



Figs. 20-24. These figures are introduced to represent a series illustrating the 

 changes undergone by the terma and its commissures, phylogenetically, with a 

 view to strengthening their homology. 



Fig. 20 is the mesal region of these parts in Desmognathus ; 

 Fig. 21, of Cryptobranchus ; 

 Fig. 22, of Rana ; 

 Fig. 23, of Emys ; 

 Fig. 24, of Anas (duck). 



(Figs. 21-24 ^'■^ from Osborn.) 



Fig. 25. Transection through the rhinencephal. X 40. 



Fig. 26. Transection through the prosencephal, with the cephalic end of the 

 supraplexus just appearing. X 40. 



Fig. 27. Shows the supraplexus dipping down between the two hemicerebrums, 

 and extending laterally through the portas to form the paraplexus. X 40. 



Fig. 28. Shows the relation of the callosum and precommissure to the adja- 

 cent parts. X 40. 



Fig. 29. A transection through the diencephal, with the caudal end of a 

 hemicerebrum on each side. X 40. 



Fig. 30. Transection through the mesencephal, with the infundibulum. X 40. 



Fig. 31. Same, farther caudad. X 40. 



Fig. 32. Mesencephal, showing the separation of the cinerea of the roof into 

 two layers. X 40. 



Fig. 33. Section at about the level of the seventh and eighth nerves. X 40. 



Fig. 34. Caudal end of oblongata, near the myel. X 40. 



Fig. 35. Shows the cerebellum, with the overlapping geminum. X 40. 



Fig. 36. Transection through the metencephal. X 40. 



