96 Trans. Acad. Sci. of St. Louis. 



Laboratory, consisted in eight heads of Amblystoma punc- 

 tatura, serial sectioned. 



The animals were of the following total lengths : 



No. 57 12mm. 



58 13mm. 



59a 17mm. 



59 19mra. 



60a 21-24mm. 



61 24-27mm. 



62 27-30mm. 



63 30-33mm. 



All of these heads were transected, except the last one in 

 the list which was cut in the frontal plane ; all sections were 

 10/i thick. 



Besides this full series of small larval heads the nasal 

 region in Amblystoma of 40-45mm. in length was studied 

 by means of serial sections and dissection. These ani- 

 mals were obtained at Woods Hole, and I take this oppor- 

 tunity to express my appreciation of the courtesies shown me 

 while finishing the work at the Marine Biological Laboratory. 

 Dissections of adult heads also were made, and frontal sec- 

 tions of an adult right nasal capsule were prepared and 

 studied. For this material I am indebted to my friend, Mr. 

 Julius Hurter. 



The ethmoidal region of Nos. 58, 59a and 60a, and the left 

 nasal sac and skeleton of head No. 62 were modeled in wax 

 after the method of Born withBardeen's ('01) modifications. 

 These are referred to in the description as stages I, II, III 

 and IV. Amblystoma of 40-45mm. is my stage V. 



The olfactory organs of Amblystoma have been described 

 by Bawden ('94) in his work on the nose and Jacobson's 

 organ. It will be necessary here to make only a brief 



