562 B. F. Kingsbury and H. D. Eeed. 



Turning now to the development of the "sound-transmitting" 

 apparatus in Ambystoma, we find that only imperfect glimpses of 

 the true development were obtained, and it is not always easy to 

 determine to which structure they refer. Wiedersheim, Parker, 

 Stohr, Killian, Witebsky, Winslow, have examined one or more stages 

 in the larval Ambystoma or Siredon (Axolotl). Wiedersheim and 

 Winslow evidently described the development of the columella; 

 Witebsky saw the independent chondrification of the columella but 

 missed the connection of the stilus with the squamosum (or palato- 

 quadrate) and drew from his observations some quite irrelevant con- 

 clusions as to the homology of the columella for which he had no 

 sufficient basis in fact, as has been pointed out by Gaupp ('08) from 

 whose paper our information is gained, Witebsky's dissertation being 

 inaccessible to us here. Stohr made his examination of the develop- 

 ment in the Axolotl only incidental to a more detailed study of the 

 development in Triton, so that he simply "confirmed" the results of 

 Parker's more extended investigation, stating that the "operculum" 

 grows out of the cartilaginous border of the fenestra vestibuli. He 

 gives no figures, so that it is difficult to interpret his results. It Avas 

 apparently the Columella (our use) that he had under observation. 

 Parker alone examined an extended series of larval Ambystoma 

 (Axolotl, Siredon) including an adult Ambystoma. For the first 

 seven stages neither his words nor his figures give indubitable proof 

 that he saw the development of the columella or recognized the stilus 

 or its connection. His description (p. 564) of the adult (Ambystoma 

 opacum) indicates that in his stapes he described the operculum.^ 

 In two points there was probably mistaken identification ; ligament 

 and ossification were doubtless absent. The descriptions of two large 

 Axolotls (8V2 and 81/4 inches long) undoubtedly applied to the 

 Columella,''' the recognition of the suspensorial connection above the 

 facial nerv^e being noteworthy. 



*"The bulging bony floor of the vestibule forms a widely crescentic bulla, 

 and in the notch the fenestra ovalis contains a small lenticular stapes, the 

 center only of which is ossified. The spiracular ligament fastens the stapes 

 to the back of the top of the suspensorium." 



'Page 559, "the stapes (Figs. 2, 4 and 5, st.) is unusually solid and pro- 

 jecting, its outstanding process looking a little forward. From that process 



