4G4 EDWAUD B. POULTON. 



cells which seem to be partially cornified. These are again 

 transitional into the ordinary fusiform cells of the rete Malpi- 

 ghii. This extremely granular cell is certainly a transition 

 into a corneous cell similar to that described in the mechanical 

 papillae of Perameles (see this Journal for January, 1883). 

 Here, however, the cell is very finely and densely granular, 

 instead of the coarse type observed in Perameles. There is an 

 exactly similar transition through polygonal finely granular 

 cells to corneous cells, even better marked in the maxillary 

 teeth which I hope to describe on a future occasion. Secon- 

 llary papillary processes enter the rete Malpighii from below, 

 and in the axis of the hor.ny papillae these processes are long 

 and fine, and from the summit of each a line of granular cells 

 extends to the very apex. Thus there is no cornified invest- 

 ment at the centre of the apex, and that which covers the sides 

 of the papilla terminates in a sharp-edged corneous ring. The 

 edges are kept sharp by the constant wear of the softer central 

 epithelium. There is reason to believe that the maxillary 

 teeth are rendered uneven in a similar manner, i. e. by the 

 wear caused in parts by the presence of very long papillary 

 processes, with lines of soft cells extending from their apices. 

 Similar lines of cells can be detected in the hard investment of 

 these lingual teeth as well as in the maxillary teeth (fig. 7, Ic), 

 but in these cases the cells are completely cornified, and their 

 arrangement in lines is only recognisable by a looser connexion 

 between them. Small secondary papillce cover the upper 

 surface of the base of the two horny papilla?. 



2. The Posterior Region is covered with a thick simple 

 epithelium resembling the rete Malpighii. The complex epi- 

 thelium of the overhanging surface ceases at the rounded angle 

 which separates it from the side of this region, but below, in 

 the slight groove which separates the posterior part of the 

 tongue from the floor of the mouth, the epithelium remains 

 complex. The same structure is continued upwards along 

 the shallow groove in front of the fold {f, figs. 1 and 2), while 

 the fold itself is covered with simple epithelium. Similarly at 

 iho sides ibin complex epithelium occurs only at the junction 



