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 nans of Salamandra maculata 25 mm. long. 

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

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



long. 

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



metamorphosis. 



ce columna ethmoidalis ng nasal glands 



ch choana no nasal organ 



ct cornu trabeculae ol olfactory lobe 



en external nans p profundus branch of the fifth nerve 



fen eth fenestra ethmoidalis pa processus antorbitalis 



fo foramen olf actorius pb planum basale 



ig intermaxillary gland pe pons ethmoidalis 



jg glands of Jacobson pt planum tectale 



jo organ of Jacobson pv planum verticale 



Id lacrimal duct 5 superficialis of the fifth nerve 



Im lamina medialis / trabecula 



It lamina extema 



