| OCR Text |
Show 1883.] TONGUES OF THE MARSUPIALS. 607 granular cells which in many other Marsupial tongues (Perameles &c.) form the transition into the upper corneous layer are slightly marked here. It is very likely that the transition described through the complex layers takes the place of the other method. There are, however, some finely granular cells in layer (4). The complex epithelium ends at the entrance into the involution for the circumvallate papilla? in the same way as at the mouths of the lateral organ (see fig. xxxi. Plate LV.). B. The Filiform Papilla, forming the limits of the papillate surface above and behind the lateral organ, are probably tactile in function. They are of small size for so large a tongue. They are similar to those described in Phalangista. Thus in many points connected with the tongue, Halmaturus is the most primitive Marsupial yet examined-in the very primitive lateral organ, in the extremely protected circumvallate papillae with bulbs nearly covering them, and in the irregular coronate papillae and the existence of scattered hair-like papillae between the latter, with no apparent tendency towards coalescence into rings. THE TONGUE OF Macropus melanops. This tongue had been kept in spirit, and the tissues were not in a condition for minute examination ; but many points of interest could be ascertained. The pieces of the tongue from which I intended to make sections I placed in spirit, gradually increasing the strength until they were finally placed in absolute alcohol, and were cut after remaining some little time in this fluid. General description.-The appearance of the tongue from above is shown in fig. vi. Plate LIV. (half natural size). This organ is evidently closely related to that of Halmaturus. The circumvallate papillae are arranged as usual, the posterior angle being exceptionally obtuse, although not to the same extent as in Halmaturus. As in the latter animal, the depressions leading into the cavities containing the papillae are alone visible from the surface and are very inconspicuous. The lateral organ (fig. vu. Plate LIV., natural size) also resembles that of Halmaturus; but the mound-like elevations are arranged in a regular curve, and the depressions have more of the normal appearance. Independent mucous glands cannot be seen in this specimen, but they may be present; filiform papillae are arranged above the lateral organ. The fungiform papillae are very abundant all along and just above the edge where the papillate joins the non-papillate surface. At the tip the junction is beneath the tongue and forms a line parallel with the contour (see fig. v. Plate LIV., natural size). On this papillate surface beneath the tip fungiform papillae are extremely abundant, and many of them are unusually large. There is little doubt that papilla? in this position are tactile. The free part of the tongue is about 00 m m . long, and there is a raphe detectable for about 80 m m . from the tip backwards. The inferior median ridge is low and wide, and the lateral grooves shallow (see fig. v. Plate LIV.). |
