No. 2.] AMPHIUMA MEANS. 405 



near the narial aperture, a tentacle or feeler, and a muscle by- 

 means of which the tentacle is retracted or protruded to guide 

 the animal in its dark underground expeditions. As I have 

 already shown, there exists in my youngest specimen of Amphi- 

 uma the atrophied remnants of this tentacular apparatus. The 

 columnar epithelial linijig of the canal is very distinct in about 

 one dozen transverse sections taken throiigJi the orbits. In some 

 of the sections I have discerned what I believe to be the degener- 

 ated retractor muscle. This apparatus in Amphi?ima has pre- 

 cisely the same relative location as in the Coecilians. For some 

 unexplainable reason, neither Hay nor Kingsley found this 

 organ in the young embryo. Hay speaks of nasal glands, 

 which, from his description, I conclude to be identical with 

 the glands I noticed in conjunction with the olfactory cavities. 

 The tentacular canal of Amphiuma cannot be mistaken for the 

 duct of a nasal gland, as it lies too far lateralward and posterior 

 to the nasal region. It will not answer for the duct of the 

 orbital gland, as it is too far inferior to the orbit, although it 

 is possible that its relation to the surrounding, parts may have 

 become somewhat distorted. However that may be, the occur- 

 rence of this degenerated structure in the young Amphiuma 

 and its complete disappearance in the adult gives unmistakable 

 evidence of the relationship of the Coeciliidae and AmpJiitimi- 

 dae. The disappearance of the ethmoid in the latter family 

 can be accounted for by the fact that the descending processes 

 of the frontals have displaced the cartilage for the ethmoid so 

 that it lies beneath the forebrain in my young specimens. The 

 nodule of cartilage between the anterior ends of the vomero- 

 palatines of the adult has no genealogical significance, so far 

 as I can discover. As before stated, the dense connective 

 tissue is being transformed into cartilage in my specimen of 

 6S mm. The cause of this formation is found in the fact that 

 the teetJi. of the lozver faiv in biting do not meet the correspond- 

 ing ones in front, but pass inside of them, pressing against the 

 roof membrane of the mouth, thereby exciting the grozvth of the 

 cartilage in the same manner as the horns originated in the Cavi- 

 cornia and Cervidae, according to Eimer (17). That the teeth 

 in the adult Amphiuma bite anterior to the summit of the car- 



