The Smooth Facial Muscles of Anura and Salamandrina. 353 



the rudimentary constrictor naris of Bufo cinereus could not be iden- 

 tical with the depressor alae nasi Collax, which, according to my 

 investigations, does not exist. 



From this examination of the descriptions of Zenker 

 and CoLLAN and their followers, I hold that there is no 

 reason to believe that the smooth nasal muscles which I 

 have described were observed by these investigators. 



4. The nasal Muscles in other species of Anura. 



In the various species of Anura mentioned below we find in 

 the nasal region the same general structure as in Ran a. In the 

 details however occur certain variations which have apparently in- 

 fluenced the development of the nasal muscles. Especially important 

 in this connection are the form of the intranasale and the position 

 of the glandula nasalis externa. 



1) Hyla arborea L. In this species we meet conditions which 

 resemble, for the most part, those occurring in Eana fusca. The 

 inferior part of the plica obliqua, however, is supported by a process 

 of the intranasale and the musculus dilatator naris is much smaller 

 than in Rana fusca, being represented by a few small bundles of 

 fibres only. The constrictor naris, on the other hand, presents about 

 the same degree of development in Hyla as in Rana fusca. 



2) Bufo cinereus Schneider. In this species the lower (caudal) 

 two thirds of the plica obliqua is supported by the iutranasale; a 

 dilatator naris is wanting and the constrictor naris is represented 

 only by small bundles of fibres about the glandula nasalis externa. 



3) Alytes obstetricans Laur. In Alytes the intranasale shows 

 about the same development as in Bufo, the glandula nasalis externa, 

 however, has moved inside of the planum terminale and lies therefore 

 within the nasal cavity. Here a constrictor naris is wanting and the 

 dilatator naris is very rudimentary. 



4| Bombinator igneus Rös. Here the intranasale reaches an 

 extraordinary development, forming, in fact, a solid support for the 

 plica obliqua (see Fig. 15) and also for the caudal wall of the ves- 

 tibule of the cavum superius. The glandula nasalis externa is also 

 removed to the interior of the nasal cavity. In this species both 

 nasal muscles are wholly wanting. 



From the above account it appears that among the species in- 

 vestigated, the nasal muscles have retained their highest development 



