86 ILLINOIS BIOLOGICAL MONOGRAPHS 186 



EXPLANATION OF PLATE 



Fig. 53. — Transverse section through the foramen olfactorius of Diemiclylus viridescens 38 mm. 

 long. 



Fig. 54. — Transverse section through the anterior part of the nasal organ of the same animal. 



Fig. 55. — Transverse section through the foramen olfactorius of the adult Diemiclylus virides- 

 cens. 



Fig. 56. — Transverse section through the pons ethmoidalis of Triton cristatus 28 mm. long. 



Fig. 57. — Transverse section through the planum basale of Triton cristatus 35 mm. long. 



Fig. 58. — Transverse section through the planum basale of Cryptobranchus alleghaniensis five 

 weeks old. 



Fig. 59. — Transverse section through the anterior end of the nasal organs of Spelerpes bilinea- 

 tus 15 mm. long. 



Fig. 60. — Transverse section just anterior to the planum basale of Spelerpes bilineatus 37 mm. 

 long. 



Fig. 61. — Transverse section through the same region of Spelerpes bilineatus 46 mm. long. 



Fig. 62. — Transverse section through the choanal region of Pletkodon erythronotus adult. 



Fig. 63. — Transverse section through the lamina medialis of the same animal. 



no nasal organ 



ol olfactory lobe 



on olfactory nerve 



oo optic organ 



p profundus of the fifth nerve 



pb planum basale 



pe pons ethmoidalis 



pm premaxillary bone 



pt planum tectale 



pv planum verticale 



s superficialis of the fifth nerve 



t trabecula 



v vomer 



