Kincssury, Columella Auris and N. Facials. 333 
of nerve to skeletal structure of extreme type. As is well 
known,' in the frog the hyomandibular nerve crosses above the 
columella and passes down behind it to its destination, whereas 
in Urodeles it passes in front of or below the same structure. 
Other cases of similar differences of relation in this region, 
mentioned in this paper, are (a), the relation of the jugular 
nerve in Necturus on the one hand and in the other salamanders 
investigated on the other hand; in the first case it passes above 
the columella (stilus columellae), in the second, below.  (b), 
Necturus also offers a difference in the relation of the internal 
mandibular branch to the quadrato-hyoid ligament. In Des- 
mognathus and Spelerpes the nerve passes on the inner side of 
the ligament; in Necturus, through the ligament, or on its 
outer side in younger individuals. Further (c), the R. jugu- 
laris in Necturus passes over the depressor mandibuli; in 
Spelerpes larvae, through it; in Desmognathus larvae, under it. 
The differences, in the last two cases at least, it seems to 
me, might possibly be explained on a more or less mechanical 
basis. The nerves (and muscles) are already developed and 
their course and positions established before the anlage of the 
columella or that of the quadrato-hyoid ligament has appeared, 
and the relations the latter structures assume when they do 
develop, has been determined for them by the position of the 
structures earlier developed. This explanation would not, of 
course, be an ultimate one. 
The nomenclature employed in the above descriptions is 
that suggested by Professor Gaupp. Columella, including 
operculum and its process, sti/us columellae, which may be 
joined to the suspensorium by an appreciable ligament—/ga- 
mentum suspensorto-columellare (operculare). \regard the sus- 
pensorio-columellar (opercular) connection in the forms studied 
as homologous. The term stilus columellae is used in describ- 
193, Gaupp, E. Beitrage zur Morphologie des Schadels. I. Primordial 
Cranium und Kieferbogen von Rana fusca. Morph. Arédeten, herausgegeben von 
G. Schwalbe, Bd. II. 
’99. ECKER’s u. R. WIEDERSHEIM’S Anatomie des Frosches, auf Grund 
eigener Untersuchungen durchaus neu bearbeitet. [II Abth. 1899, 
