626 MR E. B. POULTON ON THE [DeC. 18, 



tissue prolonged downwards from that in the axis of the papilla. A 

 few cells are also present in the upper part of the same mass. n. Nerve 

 leaving the mass in the axis of the papilla. ;". m. Dense mucosa pro- 

 longed into the papilla, where it becomes unravelled and supports the 

 nervous structures, sf. m. Striated muscle-fibres terminating m the 

 dense mucosa at the point where the latter is bending upwards to enter 

 the papilla. It would seem that contraction of these fibres must re- 

 tract the papilla, and may protect it by causing the mouth of the cavity 

 to close tightly round its upper part ; but another and opposite inter- 

 pretation is possible. 

 Fig. NXI.X71-5. Section transverse to the long axis of a circumvaUate papilla 

 of Halmattirus ualahafus at about the thickest part (see fig. xiv. Plate 

 LIV.). s. I. Superficial lamina of cornified epithelium, through which 

 the short gustatory pores pass vertically, s. ep. Stratified epithelium 

 between the outer "parts of the bulbs (the remains of that from which 

 the bulbs were developed), t. b. Taste-bulbs, s. e. I. Subepithelial 

 layer, probably consisting of elements of the nervous and fibrous tissues 

 (of the next layer), arranged in extremely fine interpenetrating net- 

 works. In addition to this arrangement straight radial fibrils are 

 seen passing from the next layer towards the bulbs. It is evident that 

 the nerve-fibres are reduced to their ultimate structural elements in 

 this layer before ending in the cells of the bulbs. /. I. Fibrous layer 

 supporting the nervous tissues and the whole papilla, continued into 

 the papilla from the dense mucosa round it (see fig. xx. Plate MV)- 

 Nerves are seen passing through this layer to that last described 

 {s.e.l). c. n. The nerves in the axis of the papiUa, gradually passing 

 outwards through the last layer (/. I.). 

 Fig. XXII. X 40. Vertical longitudinal section through one of the strongly deve- 

 loped and modified coronate papillse from the patch behind the tip 

 of the tongue of Didelphys quica (see fig. xi. s.c.j)., Plate LIV.). s. e 

 Superficial epithelium, p. h. p. Strongly cornified {c. e.) recurved 

 hook taking the place of the normal posterior hair-like papill». p. p- P- 

 Posterior papillarj- process entering the base of the latter. In this 

 section a line of cells continued from the apex of the papillary up- 

 growth can be distinguished from the cornified cells of this hook-like 

 structure, a. h. p. Anterior hair-like papilla of normal structure. 

 a. p. p. Its papillary process. This section is taken along the line 

 A-B of the next figure. 

 Fig. xxiii. X 50. Horizontal section through a similar papilla (of Biddphys 

 quica), taken along the line A-B of the preceding figure, p. h. p. 

 The posterior cornified hook is seen to possess a very singular out- 

 line. The two arms of the crescent arise outside the normal secondary 

 papillae, indicating that the structure does not entirely correspond to 

 the latter, but probably belongs in great part to the sides of the primary 

 papilla, p. p. p. The crescentic papillary upgrowth for the hook, 

 of very remarkable outline and relation to the papillary processes of 

 the normal secondary papillse. a. h. p. Anterior hair-like secondary 

 papilla (normal), s. h. p. Single hair-like papillse scattered between 

 the coronate papiUce as in some other Marsupials, and similar to the 

 normal secondary papilliE of the coronate structures. 

 Fig. XXIV. X 50. Horizontal section through a coronate papilla just in front of 

 the anterior circumvallate papilla of Biddphys quica. h. p. Hair- 

 like secondary papilla, of which there is a very unusual number. The 

 shape of the coronate papilla is very remarkable, and probably arises 

 from longitudinal coalescence. 

 Fig. XXV. X 14-5. Horizontal section through the coronate papillse (c. p.) of the 

 region halfway between the tip and the anterior circumvallate papilla 

 of Macropus melanops. Posteriorly the section is deepest, and shows 

 the single main papillary upgrowth for the whole coronate papilla 

 (c. p. p.). A. little higher the secondary papillary processes for the 

 anterior hair-like papilla are distinct («. p. p.), while the posterior 



