No. 2.] AMPHIUMA MEANS. 40 1 



trally the first inscriptio tendinea is seen just below the basihyal. 

 The remnants of some nasal glands are present along the ol- 

 factory sac. Hay found these glands better developed in his 

 specimens. The most important and interesting structure is 

 found below and external to the eye in my smallest specimen, 

 seventy-eight millimetres in length. There appears in tJiis 

 region a canal (Fig. 15) one-tentJi of a millimetre long, which is 

 availed by columnar epithelial cells extremely regular in outline. 

 External to the epithelial wall there is seen a thick layer inferi- 

 orly of degenerated tissue, which is bounded by a thin layer of 

 fibrous connective tissue. In three other specimens, eighty-eight, 

 ninety, atid ninety-two millimetres respectively, no trace of this 

 degenerate canal could be discovered, and in the smallest specimen 

 I was able to detect it on the right-hand side ojtly. Here it was 

 very clearly seen, as shown in Fig. 15. The significance of 

 this atrophied element will be discussed later. Hay (3), Kings- 

 ley (5), and Osborn (8) have to a limited extent described the 

 nervous system of Amphiuma. Owing to the fact that my 

 tissue was not prepared for the demonstration of the nervous 

 elements, I can add only one or two points of interest. The 

 brain (Fig. 14) is much shorter than in the adult, caused mainly 

 by the wedging in of the middle brain between the hemispheres 

 of the great brain. The brain viewed dorsally, excluding met- 

 encephalon, presents the outline of a longitudinal section of a 

 hen's ^g^, the anterior end corresponding to the smaller end 

 of the Q-^^. The olfactory lobes are not marked off as in the 

 adult. The brain of Siphonops annulatus, as figured by Wie- 

 dersheim, resembles to a considerable extent the brain of young 

 Amphiuma. The latter, however, is not so elongated as the 

 former. The pineal gland and pituitary body so prominent in 

 the adult are scarcely distinguishable. Hay and Kingsley have 

 described the origin and distribution of the cranial nerves suf- 

 ficiently for our purpose. My sections clearly corroborate the 

 statement by Hay that the facial nerve passes beneath the 

 columella. Kingsley failed to find the roots of the fifth nerve. 

 My sections shoiv but one root. The dorsal ganglion in connec- 

 tion with the twelfth nerve is quite large, being at least one- 

 third the size of the gasserian ganglion. 



