THE NASAL SKELETON OF AMBLYSTOMA 

 PUNCTATUM (Linn.) 



Egbert J. Terry.* 



The nasal skeleton of the Urodela presents itself in a num- 

 ber of forms which differ more or less widely from each other 

 as well as from the types met with in the Anura; that is to 

 say, comparisons of the fully formed skeletons have shown 

 apparently no common order of structure. 



One object of this work was to study the early stages 

 in the chondrification of the nasal skeleton of an Amphi- 

 bian and to compare them with the developing nasal skele- 

 tons in others in the hope of finding resemblances which 

 in the adults are not marked. For this purpose Ambly- 

 stoma was selected because it is a typical form and because 

 a certain part of the work has already been accomplished. 

 A second object concerned the plan of chondrocranial forma- 

 tion and perfection in the ethmoidal region for which Am- 

 blystoma seemed suitable in the vigorous development of its 

 cartilaginous head-skeleton. The bony framework of the 

 nose has not been included in the present investigation. 



Winslow ('98) used Amblystoma as the basis of his work 

 on the chondrocranium describing five stages, viz., in the 

 body-lengths of 10, 11, 12, 39 and 69 mm., and though he 

 does not deal specially with the nasal skeleton, his discrip- 

 tions of this region are full. I have selected and described 

 stages between the total lengths of 12 and 39 mm., but was 

 unable to obtain animals between 45 and 69 mm., the want 

 of which was much felt. 



The excellent series of young larval heads which were 

 at my disposal were kindly loaned by my friends Pro- 

 fessor and Mrs. Simon H. Gage, to whom I offer my best 

 thanks. This material from the Cornell Embryological 



* Presented tx) The Academy of Science of St. Louis, Feb. 6, 1906. 



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