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 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 naris p profundus branch of the fifth nerve 
fen eth fenestra ethmoidalis pa processus antorbitalis 
fo foramen olfactorius pb planum basale 
ig intermaxillary gland pe pons ethmoidalis 
Ig glands of Jacobson pt  planum tectale 
jo organ of Jacobson pv — planum verticale 
ld lacrimal duct s superficialis of the fifth nerve 
lm lamina medialis t trabecula 
le lamina externa 
