TONGUE OF PERAMELfiS NASUTA. 83 



In the anterior papillae the ring is more perfect and the in- 

 complete point is much narrower. Hence longitudinal vertical 

 sections, which do not strike this point, show a well-developed 

 upward growth anteriorly (compare the ends of fig. 4 in this 

 respect, and the ring p" of fig. 7 with p' of fig. 6). This 

 explains why the vertical longitudinal sections (figs. 8 and 11, 

 and the anterior [i5] end of fig. 4) do not often show the con- 

 vex surface within the ring sloping down to be continuous 

 with the anterior wall. Horizontal sections of course do 

 indicate this. 



At higher levels the ring gives off small secondary papillary 

 processes for the hair-like papillae. These are first met with 

 in the feebly developed anterior horns of the ring, and gradu- 

 ally extend backwards as the ring (becoming semicircular, finally 

 a semilunar remnant) rises higher. Finally, the last semilunar 

 trace of the ring gives origin to the largest and most posterior 

 papillary upgrowths (fig. 6 shows all these changes very dis- 

 tinctly in passing from ^ to ^). Although, strictly speaking, no 

 papillary upgrowth can take place in the exact anterior margin 

 of the ring (incomplete), it is common to meet a papillary 

 process almost at this point at a rather higher level (fig. 6, &c.). 

 This is due to a papillary process rising a little obliquely from 

 one side to the anterior point, and explains why two hair-like 

 ])apill8e are almost invariably cut through in longitudinal ver- 

 tical sections (figs. 4 and 11), although the corresponding 

 papillary upgrowth for the anterior papilla is often wanting 

 (see posterior end of fig. 4). The upper surface of the papilla 

 within the ring of hair-like papillae corresponds to the under 

 surface within the ring-like extension of the papillary process 

 from the mucous membrane. The concave upper surface cor- 

 responds to the convex lower surface, and the downward 

 anterior slope of the latter to the upward posterior slope of the 

 former. From side to side there is a regular concavity above 

 corresponding to a regular convexity below (fig. 5). The 

 curves are, however, always more marked below than above, 

 as the great thickness of intervening cells tends to partially fill 

 up the hollows (figs. 5, 11, &c.). The inferior convexity is 



