1883. J TONGUES OF THE MARSUPIALS. 627 



processes are still fused into a single upgrowth, crescentic in section 

 {p-p.p-). At a higher level than is shown in this section the complete 

 ring of secondary processes would be distinct. Hence the posterior 

 papdlarj' processes are given off at a higher level (compare fig. xxvi.). 

 •s. h.p. Single hair-like papilla3, as in flg. xxrn. This section shows 

 that the upgrowths for the isolated h.ar-like papillno are very distinct 

 from those of the coronate papillae even at the lowest levels. 



Fig x'cvi. xl4 5. A single coronate papilla from the region between the two 

 anterior circumvallate papillte of Macropus melanops, shown in per- 

 spective from the left side. The secondary papillae are probably finer 

 than in reality. 



Fig. XXVII. X 10. Vertical longitudinal section along the middle line of the papil- 

 late surface in front of the anterior circumvallate papillaj of Halniaturiis 

 ualabatus. The section shows the relation of the isolated fine papillaa 

 (s. h. p.) to the coronate papilLx {o. p.). 



Fig. xxviir. X 40. Horizontal section through the coronate papillaj of Halmaturus 

 ualabatus, taken in the middle line just anterior to the postei-ior 

 circumvallate papiUa. This also shows the relation of the isolated 

 (s. k. p.) to the coronate papiUte (c. p.), and also indicates that the 

 secondary papilla on the latter are not always regularly arranged 

 in the ring. The posterior side of a coronate papilla can sometimes 

 be detected bj* the fact that some of the posterior secondary processes 

 remain stiU coalesced, although they are distinct at other points of 

 the circumference, i. h.p. Single hair-like papillas within the ring 

 of some of the coronate papillre. 



Fig. XXIX. X 40. Vertical longitudinal section through a coronate papilla (vertical 

 transverse through the organ), just above the lateral organ of Halma- 

 turus ualabatus. The figure shows the relations of the four layers of a 

 complex epithelium to the papillary structure. The layers are : — 1, 

 staining moderately, the cells fusiform and nucleated ; 2, a thin layer, 

 behaving with reagents as if the cells were cornified ; 3, deeply stain- 

 ing, elongated cells with long thin nuclei ; 4, a layer presenting all 

 the characters of normal refe Malpighn. The distribution of layer (2) 

 in the secondary papillse (p. h. p. and a. h. 'p.) also indicates that it is 

 cornified. The same layers are met with in the smooth epithelium 

 beneath the papillate sm'face (see fig. xxxi.). The shading is diagram- 

 matic. In other parts of the organ, the distribution of layer (2) is 

 more symmetrical in the secondary papillaj. 



Fig. XXX. X 50. Vertical longitudinal section thiough a coronate papilla from 

 the surface above tlie tip of the tongue of Phalangistu vulpina. The 

 figure shows the arrangement of the cells mucli resembling that de- 

 scribed in Perarnelcs, but more complex. The normal lower layer 

 (». I.) graduates into attenuated granular cells («. <?.), passing through a 

 massof similar cells of which the nuclei stain deeply (pi. c), into the very 

 attenuated cells of the posterior process (|;. '■.), in which hardly any 

 nucleus can be detected. Above, in the centre of the main papilla, 

 the cells are still granular, but swollen and non-staining {s. c), while 

 remnants of the nucleus can be often detected. Higher still, and 

 towards the posterior secondary papilla, the cells again become attenu- 

 ated, rarely nucleated, and deeply staining (a', c'.), and they are con- 

 tinued on to the posterior papilla?. The swollen cells pass directly 

 into the attenuated cells of the anterior papilla witliout forming a layer 

 in the main coronate papilla. All the secondary papillas also derive 

 cells from their own papillary upgrowths, and also from the super- 

 ficial epithelium surrounding them. The latter is simple and of the 

 usual structure. 



Fig. XXXI. xl4o. Vertical transverse section through one of the elongated de- 

 pressions of the lateral organ of Halmaturus ualahatus. The depression 

 {g. d.) is seen to present all the characters of a gland-duct, and a 

 secondary duct opens into it above the region of the taste-bulbs {t. b.). 

 In the epithelium the four layers described in fig. xxix. are shown. 



