DEVELOPMENT OF TKETH IN HATTERIA PUNCTATA. 187 



lamina dies out immediately posterior to this point. The 

 seventh palatine tooth is, like the last maxillary, fully formed 

 and fused with the bone. lu this case the dental lamina, 

 which reappears here and is continued some little distance 

 backwards, bears two enamel organs, both in the eai-liest 

 stages. Here, again, we have an indication of a cessation of 

 tooth formation, but from the condition in the adult, and 

 from the above observations, this is much less prolonged than 

 in the maxilla. The two early enamel organs are doubtless 

 destined to form teeth of the uniform series, which are in 

 the adult proportionately much more numerous here than in 

 the maxilla, commencing their formation as we see at an 

 earlier period. 



1 have found no signs of vomerine teeth in this speci- 

 men. 



The number of teeth in the two halves of the mandible are 

 twenty and twenty-one respectively. Although we may still 

 single out three more conspicuous front teeth on either side, 

 these are not the same as those of the newly-hatched animal, 

 or even of the last specimen. The second is clearly a succes- 

 sional tooth (fig. 26, t.s. 1), and a comparison shows that it 

 has replaced Nos. 2 and 3. In Baur's specimen it was still 

 below the gum. In addition lo this, as fig. 26 shows. I found 

 a second successional tooth, deeply seated below the fourth 

 and fifth in order. I have confirmed these points in sections, 

 and find that the first tooth in order shows signs of being 

 deciduous. There is a conspicuous dental lamina attached 

 to the side of the internal fossa nearest the tooth. It extends 

 round the anterior curve of the jaw, and dies out just posterior 

 to the fifth in order. It has a swelling between the second and 

 third teeth, which is perhaps an early enamel organ. I have 

 found no other indications of tooth change in the mandible. 

 Returning to the macroscopic features of the mandibular 

 teeth we find that, posterior to the first two, there are thirteen 

 teeth belonging to the alternating series. Posterior to these, 

 again, are five larger teeth uniform in size. In the last 

 specimen we found also thirteen alternating teeth, and three 



