284 H. H. WILDER, 



trichterartig sich erweiternden Tracheen auf eine lange Strecke zu je 

 einem continuirlichen, hyalinen, niedianwärts ausgezackten Knorpelband 

 zusammenschmelzen." 



This author seems to be the first who has recognized the re- 

 solution of the tracheal pieces into separate elements, although in the 

 case of Siren he has represented the dismemberment as greater than 

 in the cases which have come under my examination. The case 

 examined by Wiedersheim may have been one with excessive separa- 

 tion of parts, as in Necturus (Fig. 6), or the median points upon the 

 lateral pieces may have been interpreted as separate, in which case 

 they would appear as two rows. This is rendered more probable by 

 the fact that the points are bordered with a reddish brown pigment, 

 and that the lateral continuous strip, being without that pigment, is 

 exceedingly difficult to demonstrate. 



The condition described in ÄmpJiiuma is accurately expressed, 

 although the conclusion is just the reverse of my own, as shown in 

 the young form. The "Zusammenschmelzen" is the primitive condition 

 and the "Knorpelsplitterchen " the derived. My own former descrip- 

 tion of the laryngeal cartilages of Siren is incorrect, but the error 

 may be easily explained. The description was based upon a pre- 

 paration under the lens, supplemented by a transverse series through 

 the anterior end. By the first method I demonstrated the more 

 posterior continuous tracheal piece as well as the independent ary- 

 taenoids. The second method showed me the hyaline structure of 

 the arytaenoids, as well as the fibro-cartilaginous nature of the de- 

 generate tissue continuous with it. My series stopped there, and I 

 described the arytaenoids as hyaline and the tracheal pieces as fibro- 

 cartilaginous (No. 11, p. 678—679). The figure given in the plate 

 accompanying the paper shows my uncertainty. The theory advanced 

 in that work regarding the origin of the arytaenoids was presented 

 only as a tentative hypothesis, and became replaced by the present 

 theory in my paper of 1892. 



Menopoma alleghaniense. 

 This conforms very closely to the condition in the two preceding. 

 Henle's figures representing a fusion of the tracheal elements across 

 the middorsal line 1 regard as erroneous. Hence the conclusion that 

 this represents a stage in the formation of tracheal rings falls to 

 the ground. 



