352 Henry L. Bruner 



his views in regard to the structure of the nasal region of Rana in 

 the following manner: 



»Die äußeren Öffnungen der Nasenhöhle können bekanntlich 

 durch kleine, von der Cutis bedeckte und auf den Zwischenkiefer 

 befestigte Knorpel geschlossen werden. Die Zwischenkiefer selbst 

 sind mit dem Oberkiefer und dem an das Siebbein ansetzenden 

 Nasenknorpel beweglich verbunden, so dass mau am todten Frosch 

 durch Hin- und Herbewegen derselben die Nasenlöcher öffnen und 

 schließen kann; dass dieser Akt bei der Respiration auf dieselbe 

 Weise bewirkt wird, folgt daraus, dass man in der That bei lebhaft 

 respii-irenden Fröschen Bewegungen der Zwischenkiefer beobachtet« 

 (page 25). 



These views of Volkmann and Heinemann found a certain 

 measure of justification also with Ecker (16), who, as above remar- 

 ked, denied the existence of the third muscle of Duges. 



A thorough and satisfactory investigation of the question was 

 finally made by Gaupp (20 and 21), who not only denied the 

 existence of the muscles described by Zenker, but proved also that 

 such muscles would be entirely superfluous, since both the opening 

 and closing of external naris of Rana is effected by means of a 

 peculiar combination of levers, which has been briefly described 

 above. With these conclusions my own observations are in entire 

 accord. 



There remains yet for consideration a description made by CoL- 

 LAN (1 2), who studied the nasal muscles of Bufo cinereus Schneider. 

 Collan believed that he saw in this species the following muscles: 

 1) m. intermaxillaris, 2) m. dilatator narium, and 3) m. depressor alae 

 nasi. The two first muscles are identical with the two first muscles 

 of Duges; the third muscle, however, springs, according to Collan, 

 from cartilage close to the margin of the fronto-nasale and inserts 

 on the outer margin of the nasal opening. This muscle was sup- 

 posed to close the nasal opening. 



The third muscle mentioned by Collan is the only one which 

 need be considered here. Its general location seems to be the same 

 as that of the constrictor naris of Rana. In direction and attach- 

 ments, however, as well as in function, the constrictor naris differs 

 entirely from the depressor alae nasi Collan. I find, moreover, on 

 examination of Bufo cinereus that the constrictor naris of that species 

 is quite degenerate, its dorsal part, which is strongest in Rana, 

 being almost wholly wanting. I am led therefore to conclude that 



