The Smooth Facial Muscles of Anura and Salamandrina. 319 



the epithelium, although its value, as estimated by Marcacci (32) 

 and Camekano (10), seems to have been over-estimated i. 



The literature of this subject has already been reviewed by 

 others and does not need special attention here. A summary of 

 results is presented by Gaupp (20) and more detailed accounts may 

 be found in the works of Martin (33), Bert (1) and Heinemann (24). 



II. The 3Iechaiiism for Closing the External Nares in the Salamandrina. 



From the above description it is evident that the secure closing 

 of the mouth and nares is a necessary condition to inspiration in the 

 luug-bearing amphibians. In " the salamanders these two functions 

 are assigned to entirely different mechanisms. The jaws with their 

 solid bony framework and their cushion-like lips (compare Figs. 1 

 to 6, PI. XVII) are simply pressed together by the masticatory 

 muscles (masseter, temporalis and, in some species, a pterygoideus), 

 a description of which will be unnecessary. The external nares of 

 the salamander are opened and closed by a special muscle apparatus, 

 which must now receive attention. Preparatory to this description, 

 however, and as a basis for future comparison, I must review some 

 features of the anatomy of the nasal region of the Salamandrina. 



1. General Anatomy of the Nasal Region of the Salamandrina. 

 The general anatomy of the nasal region of the Salamandrina 

 is well known through the work of Parker (37 and 38), Wiedersheim 

 (53', Born (4), Seydel (45), and others. In the following sketch 

 are contained only those facts which have a special bearing on the 

 present investigation. All points have been verified on Triton alpestris 

 Laur., which I shall use as a type of the entire group. For com- 

 parison see Figs. 1 to 7, PI. XVII, taken from Salamandra maculosa, 

 Desmognathus fusca and Amblystoma tigrinum. 



The two nasal cavities of Triton alpestris are enclosed each in 

 a cartilaginous capsule, which is strengthened and supplemented by 

 the superimposed bones. In the walls of each capsule are four large 

 fenestrae (see diagram. Fig. 7, PI. XVII): in the roof a fenestra dor- 

 salis; in the floor a fenestra ventralis, which contains the internal 



1 More recently the bucco-pharj-ugeal respiration of the liinglcss sala- 

 manders has been studied also by Anne Ide Barrows (Anatom. Anzeiger. 

 Bd. XVIII. 1900) and II. H. Wilder (American Naturalist. Vol. XXXV. 1901). 



