86 
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ILLINOIS BIOLOGICAL MONOGRAPHS [86 
EXPLANATION OF PLATE 
53.—Transverse section through the foramen olfactorius of Diemictylus viridescens 38 mm. 
long. 
54.—Transverse section through the anterior part of the nasal organ of the same animal. 
55.—Transverse section through the foramen olfactorius of the adult Diemictylus virides- 
cens. 
56.—Transverse section through the pons ethmoidalis of Triton cristatus 28 mm. long. 
57.—Transverse section through the planum basale of Triton cristatus 35 mm. long. 
58.—Transverse section through the planum basale of Cryptobranchus alleghaniensis five 
weeks old. 
59.—Transverse section through the anterior end of the nasal organs of Speler pes bilinea- 
tus 15 mm. long. 
60.—Transverse section just anterior to the planum basale of S peler pes bilineatus 37 mm. 
long. 
61.—Transverse section through the same region of Speler pes bilineatus 46 mm. long. 
62.—Transverse section through the choanal region of Plethodon erythronotus adult. 
63.—Transverse section through the lamina medialis of the same animal. 
columna ethmoidalis no nasal organ 
choana ol __ olfactory lobe 
cornu trabeculae on olfactory nerve 
foramen olfactorius oo _ optic organ 
foramen orbito-nasalis p profundus of the fifth nerve 
intermaxillary gland pb planum basale 
organ of Jacobson pe — pons ethmoidalis 
lacrimal duct pm __ premaxillary bone 
lamina externa pt  planum tectale 
lamina medialis pv _ planum verticale 
maxillary bone s superficialis of the fifth nerve 
nasal bone t trabecula 
nasal glands v vomer 
