■The Smooth Facial Muscles of Anuia and Salamandrina. 327 



they bore their way and finally reach the caudal margin of the nasal 

 opening, where they discharge singly. The significance of this 

 peculiar condition is evident. The contraction of the constrictor naris 

 will produce compression of the medial tubules of the gland and cause 

 a discharge of their secretion upon the margin of the nasal opening. 

 This result is made certain by the fact that the portion of the con- 

 strictor naris which is penetrated by the glandular tubules is composed 

 of a network of crossing fibers. The effect of their contraction is 

 thus much intensified. 



In Amblystoma, also, a forward movement of the glandular se- 

 cretion in the posterior part of the gland will probably follow the 

 contraction of the two dilatator muscles. In this species, however, 

 the effect of such contraction upon the contents of the tubules will 

 be less marked on account of the absence of a bony roof in the 

 posterior part of the fenestra rostro-lateralis. These less favorable 

 conditions are counter-balanced, however, by the relations existing 

 between the glandula nasalis externa and the constrictor naris in 

 the immediate neighborhood of the nasal opening. 



From the preceding investigation, then, the following conclusion 

 may be drawn: — In Triton alpestris, Salamandra maculosa, 

 and Amblystoma tigrinum there exists between the nasal 

 muscles and the glandula nasalis externa a functional 

 adaption, by virtue of which the secretion which favors 

 the secure closing of the nasal opening is discharged upon 

 the margins of this opening by the contraction of the nasal 

 muscles. 



The glandula nasalis externa of the Salamandrina was })robably 

 observed first by Wiedersheim (54), who also called attention to the 

 rich glandular development in the nasal region of Plethodon and its 

 allies. Born (4) located the external nasal gland of Triton in a 

 connective tissue thickening^ (»Bindegewebswulst«) of the nasal wall 

 and placed the opening of its duct somewhat doubtfully inside of the 

 nasal cavity. Born also described the external nasal gland of Rana, 

 together with its duct. The homology of this gland with the external 

 nasal gland of the salamander was recognized as very probable. 

 Kiese (41) followed Born in regard to the location of the external 



I The identity of this connective tissue thickening with the nasal muscle 

 thickening has already been shown. 



