84 ILLINOIS BIOLOGICAL MONOGRAPHS [84 



EXPLANATION OF PLATE 



Fig. 41. — Transverse section through the anterior part of the nasal organ of Amblystoma punc- 

 tatum 13 mm. long. 

 Fig. 42. — Transverse section through the middle region of the nasal organ of the same animal. 

 Fig. 43. — Transverse section through the choanal region of Amblystoma punctatum 20 mm. 



long. 

 Fig. 44. — Transverse section through the pons ethmoidalis of Amblystoma punctatum 25 mm. 



long. 

 Fig. 45. — Transverse section just anterior to the planum verticale of Amblystoma punctatum 



55 mm. long. 

 Fig. 46. — Transverse section through the planum verticale of same animal. 

 Fig. 47. — Transverse section through the planum verticale of Amblystoma punctatum at the 



end of metamorphosis. 

 Fig. 48. — Transverse section through the lamina medialis of same animal. 

 Fig. 49. — Transverse section through the external naris of Salamandra maculala 25 mm. long. 

 Fig. 50. — Transverse section through the choana of the same animal. 

 Fig. 51. — Transverse section through the fenestra ethmoidalis of Salamandra maculala 38 mm. 



long. 

 Fig. 52. — Transverse section through the planum basale of Salamandra maculata at the end of 

 metamorphosis. 



ng nasal glands 



no nasal organ 



ol olfactory lobe 



p profundus branch of the fifth nerve 



pa processus antorbitalis 



pb planum basale 



pe pons ethmoidalis 



pi planum tectale 



pv planum verticale 



s superficialis of the fifth nerve 



t trabecula 



