DEVELOPMENT OF TEETH IX HAITERLA PUNCTATA. 171 



with two dentitions, the smaller tooth representing 

 an earlier set, and the larger a later one. The same is 

 true of the premaxillary teeth, where only the second belongs 

 to the earlier set. The interpretation of the epithelial strand 

 lingual to the smaller teeth (fig. 6, r. d. I. ; fig. 4, r. d. I.) as a 

 residual dental lamina seems to me to be justifiable, although 

 at later stages, and at this stage in the lower jaw (fig. 5, 

 man. lin.), epithelial ingrowths of a different nature arise, 

 which produce some uncertainty. The fifth pair of maxillary 

 teeth form an exception to the regular alternation, inasmuch 

 as though they resemble the larger teeth in most respects, 

 they have an apparent residual dental lamina. This fact has 

 an interest in view of the development of a succession al tooth 

 at this point at a much later stage. 



Labially to the enamel organs the epidermis is beginning 

 to grow down into the mesoderm in the form of a baud of 

 cells more or less closely connected with the enamel organs 

 or with the dental lamina in rhe intermediate regions (figs. 

 4, 5, 6, 7, m. lah.). This is the labio-dental strand, and its 

 further development will be seen in later stages. 



The most anterior indication of the palatine dental 

 lamina occurs at the level of the sixth pair of maxillary teeth. 

 The epidermal ingrowth is anteriorly a solid roundish mass 

 of cells, which, traced backwards, is found to assume in 

 section a crescentic form, the attachment to the epithelium 

 being by the convex side of the crescent. The inner limb 

 is the one more closely related to the enamel organs, and 

 represents the dental lamina. The outer limb, on the other 

 hand, is more independent (figs. 4 and 5, p. lah.), and repre- 

 sents a glandular ingrowth, the relations of which will be 

 presently described. The most anterior tooth of the palatine 

 belongs to the first (embryonic) dentition, and is situated 

 linguuUy to the dental lamina (fig. 4, paZ. 1). It is a more 

 or less triangular fragment of dentine, completely enclosed in 

 epidermis, and on the point of being shed. Its position is 

 exceptional, as the teeth of this series are usually labial to 

 the dental lamina; but I do not attach much importance to 



