146 



Inez Whipple Wilder. 



The spiral thickening in the wall of the nasal cavity is shown by 

 histological examination to be composed of a mass of involuntary 

 muscle fibers, which, although somewhat interlaced, reminding one 

 of the relation of muscle fibers in the mammalian tongue, may be 

 resolved into two distinct sets plainly to be identified as the constrictor 

 naris and dilatator narls, which have been so fully worked out by 

 Bruner '96 and '01, in various genera of the Salamandrida (cf. Figs. 

 1, 2, 3, also Plate I, Fig. C). 



The constrictor naris of Amphiuma is especially well developed. 

 It arises from the inner surface of the nasal cartilage near the 



Fig. 3. — Transverse section posterior to Fig. 2. X 16 2/3. Abbreviations: 

 CO, cross section of the constrictor muscle. Other abbreviations as in previous 

 figures. 



fenestra rostralis and extends first posteriorly and dorsally, then, 

 after making a loop which partially encircles the nasal passage, it 

 passes anteriorly and mesially to its insertion into the epithelium 

 covering the dorsal and mesial portions of the spiral fold. The duct 

 of the lateral gland lies in the concavity of this horseshoe-shaped 

 muscle, the muscle itself constituting the thickening in the wall of 

 the cavity through which the duct was described as passing. (Cf. 

 Figs. 1, 2, 3, and Plate I, Fig. C.) 



The second muscle, the dilatator nans, arises posterior to the loop 

 of the constrictor naris, from the inner surface of the cartilaginous 



