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



and the caudal lip of the columella appear in the lateral wall of the 

 prominence. In all essentials, save as noted, the sound-transmitting 

 apparatus of the adult is like that of Amphiuma. 



General. 



In perusing the preceding portion of this paper, it will have 

 become obvious that considerable confusion in the interpretation 

 of the sound-transmitting apparatus in Amphibia, — particularly the 

 Urodela, — has been caused by discrepant statenients and conflicting 

 descriptions of the conditions existing in the different forms. The 

 differences that apparently existed concern principally (a) the rela- 

 tion to the suspensorium, (b) the relation of the facial nerve to the 

 stilus columellas, (c) the mode of development of the fenestral struc- 

 tures. 



The S'uspensorial Connection. Gaupp in his paper on the sound- 

 transmitting apparatus of Vertebrates ('98) was led to the conclu- 

 sion that there existed two types of connection between the suspen- 

 sorium and the skeletal element filling the fenestra vestibuli, — one 

 above and one below the facial nerve, and the same view has been 

 taken by Driiner ('03). Gaupp later ('05) says: "Die oft citierte 

 Angabe von Wiedersheim, dass der Nerv bei alien Urodelen ohne 

 Ausnahme iiber diese Briicke hinwegiauf e, ist irrig ; vielmehr scheint 

 der Verlauf der i^Terven ventral von der fraglichen Briicke das 

 haufigere zu sein. Letzteres findet sich bei Amphiuma (Hay 1890, 

 auf Grund eines von Prof. Norris hergestellten Modelles kann ich 

 diese Angabe bestiitigen), Siredon (Hasse 1873, Parker 1877) und 

 ^ahlreichen anderen Urodelen (Proteus, Desmognathus fusca, 

 Spelerpes bilineatus, nacli soeben veroffontlichten Untersuchungen 

 von Kingsbury) ; der Verlauf des E. jugularis facialis iiber die 

 erwahnte Verbindung findet sich bei JSTecturus (Huxley) und Proteus 

 (Driiner, Kingsbury). Es sind somit 2 verschiedene suspensorio- 

 columellare Briicken aus einander zu halten, eine iiber und eine unter 

 dem Facialis (Gaupp 1899)." 



For this divergence of statement, Huxley seems to have been 

 primarily responsible, inasmuch as in E^ecturus he described a 

 "Ligamentum suspensorio-stapediale" and stated that "the hyo- 



