568 B. F. Kingsbury and II. D. Reed. 



above." We are able to confirm these early observations and in the 

 light of the changes which take place in Ambystoma at transforma- 

 tion, offer an interpretation of the presence of the fourth process 

 connecting the palatoquadrate with the ear capsule. Undoubtedly 

 as in Ambystoma the columella becomes fused with the margin of 

 the fenestra and maintains its connection with the suspensorium 

 through the stilus which is without doubt the cartilaginous process 

 from the fenestral lip to the quadrate cartilage seen by Wiedersheim. 



We feel no hesitation in offering this interpretation of the structures 

 in this form even though developmental stages have not been studied 

 by us. The sound-transmitting apparatus in Salamandra is in all 

 essential respects identical with that of Ambystoma in which a very 

 large number of developmentad stages have been studied carefully, 

 permitting an interpretation of the adult condition which without 

 them would be difficult. Fuchs ('07) has figured and described the 

 chondrification of the otic capsule in Salamandra, giving in some 

 detail the formation of the fenestra vestibuli and operculum. Em- 

 ploying the nomenclature of Gaupp, he describes the operculum as 

 formed chiefly by a cutting out of the already chondrified ear capsule 

 and partly by the chondrification of the chondroblastema filling in 

 the fenestra. The latter he recognizes existent from the beginning 

 as an unchondrified portion of the otic capsule. The development 

 of the Operculum of Salamandra he undoubtedly gives correctly 

 and in the figures of models of three stages shows it forming upon 

 the medial and caudal sides of the fenestra in the m,anner stated 

 above just as the operculum is formed in Ambystoma and in Triton 

 presently to be described. He neither discusses nor shows in his 

 figures, however, the process described by Wiedersheim, the detailed 

 development of which in this forai would he of particular interest. 

 ]^o hint is given of its origin or relations except in Fig. 3 on page 

 11 where a slight projection from the dorsal boundary of the fenestra 

 appears to be what we are inclined to interpret as the caudal tip of 

 the columella. A comparison might also be made between his Figs. 

 3, I, and our Figs. 1 and 23 (PI. I) of Ambystoma and Fig. 27 (PI. 

 II) of Triton. 



Fuchs gives no intimation of the ages or sizes of the larva? or 



