736 Dr. J. BEARD, 



Probably in more mature animals both outer- and enamel epithelia 

 disappear. — Evidently sucb is the case in Myxine. 



As we have seen, except for the presence of a very small cap of 

 enamel at its apex, the tooth is destitute of enamel, and although 

 figs. 1 and 7 were taken from a fully developed and powerful median 

 tooth, there is no trace of enamel in the region of the tooth on which 

 the enamel epithelium rests. 



Whatever may be the case in the teeth of other animals, the evidence 

 does not go to show that in the Myxinoid tooth the enamel epithe- 

 lium forms the enamel. — On the contrary, everything appears to 

 point to its having other functions. 



Finally, I ought to point out the curious pyramidal arrangement 

 of the cells of the stratified epithelium above the enamel-cap (fig. 7). 

 In my preliminary paper I stated that these teeth present nothing 

 aequivalent to the so called enamel organ of other teeth. The dis- 

 covery was only made after a great many sections of Bdellostoma teeth 

 had been prepared, and then I was only able to find it in one tooth 

 near the close of the research. Afterwards I got portions of it in 

 several. 



Although I have made a great many teeth sections from several 

 individual Myxine (such sections are easily prepared from the animal), 

 I have not found this enamel organ in any tooth. One Myxine was 

 obviously a young individual, but its teeth presented no enamel epi- 

 thelium. Probably it disappears sooner or later ; its position with refer- 

 ence to the odontoblast cone cannot be a very favourable one for 

 nutritive purposes. 



The teeth of Myxine. 



As the teeth of Myxine possess nearly the same characters as 

 those of Bdellostoma they need not detain us long. 



I have figured a longitudinal section of a Myxine tooth under 

 low magnification in fig. 11, and a small portion of the apex of the 

 odontoblast cone under high magnification in fig. 4. 



The arrangement of the teeth was given in the extract from Jo- 

 hannes Müller, and it must be remembered that the members of 

 each row of lingual teeth are united together by their horny cones, 

 like those of Bdellostoma ; thus forming compound horny teeth with 

 true odontoblast pulps underneath them. 



