The Lateral Nasal Glands of Amphiuma. 147 



capsule, and from the premaxillary bone, which upon the ventral 

 side supplies the deficiency of the latter. From this origin it passes 

 anteriorly to a somewhat extensive insertion into the nasal epithelium 

 posterior and ventral to the opening of the duct. Many of its fibers 

 appear, however, to end within the belly of the constrictor muscle. 



The function of these muscles is very evidently the closing and 

 opening of the nasal passage. The constrictor muscle, since its origin 

 is anterior to its insertion, pulls forward and downward upon the 

 spiral fold causing this fold to approach the opposite wall of the 

 nasal passage, which at this point has a very narrow lumen. More- 

 over, the increase in thickness of the whole muscle mass incident to 

 the very act of contracting causes the mass to press inward and 

 forward, and thus helps to close the lumen. The dilator muscle, 

 on the other hand, pulls posteriorly upon both the spiral fold and the 

 belly of the constrictor muscle itself, and thus by its contraction 

 opens the passage again. 



The spiral fold is thus in structure and function like the crescentic 

 fold which closes the external naris of the Salamandrida (Bnmer 

 '96 and '01), differing only in the fact that it lies, not at the external 

 orifice, but at the inner end of the introductory passage. Because of 

 this location, the movements of the spiral fold of Amphiuma cannot 

 normally be observed, as can those of the crescentic fold of the 

 salamandrids ; however, in a living specimen which was in my pos- 

 session there was a slight malformation of one external naris (proba- 

 bly due to an injury), so that the introductory passage was rendered 

 funnel-shaped, and the movements of the spiral fold at the inner end 

 of the funnel could be readily observed; As in the lunged salaman- 

 drids, the closure of the nasal passage of Amphiuma occurs during 

 pulmonary respiration, and the function of the constrictor and dila- 

 tator muscles is undoubtedly associated with this act. 



As to the gland itself, it presents superficially, as has been said, 

 an acinous appearance (Plate I, Fig. D). The posterior portion 

 particularly, shows a surface made up of numerous rounded emi- 

 nences, very compactly massed together in definite lobes. However, 

 serial sections through the gland, particularly in immature specimens, 

 prove that it is fundamentally tubular in structure, but with modifi- 



