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Show 614 MR. E. B. POULTON ON THE [DeC. 18, the possession of two anterior circumvallate papilla?, following Halmaturus, and a posterior papilla much resembling that of higher animals. THE TONGUE OF Belideus breviceps. This specimen had been preserved in spirit, and although unsuitable for minute work I was able to make out a great many interesting points. The hardening was conducted as in Macropus. General description.-The size and shape of the organ, as seen from above, are shown in fig. x. Plate LIV. (natural size). The tip of the tongue had been injured by the teeth of the animal and was bent down so as to be invisible from above; but I think that this is accidental, and have taken this view in the drawing. The contour of the tip of the tongue in Acrobates bears out this view. The posterior circumvallate papilla is large and radially symmetrical, showing a large circular area on the surface ; the two anterior papilla? are not radially symmetrical, and are nearly hidden from view in narrow, slit-like, oblique depressions. Thus the arrangement is an exaggeration of that met with in Phalangista (compare figs. VIII. and x. Plate LIV.). The filiform papillae are normal in appearance and position. There is a lateral organ just below the bases of the anterior filiform papilla?, invisible from above. Four or five grooves are present, which are very small and recognizable with difficulty. The free part of the tongue appears to be about 11 m m . long. There is a sharp inferior median ridge with the two grooves. Minute Structure.-I. Gustatory Structures. A. Circumvallate Papilla.-The posterior papilla resembles that of Perameles in possessing a ganglion within it, which is not prolonged into the base as in Phalangista. Nerve-cells are very numerous in the axis of the base, extending upwards for half the height of the papilla. The summit of the papilla is beset with small secondary papillae, thus resembling Phalangista rather than Perameles, but the whole shape more resembles the latter (compare figs. XVII. and XVIII. Plate LIV.). The papilla is certainly radially symmetrical, and the irregularity shown in fig. XVII. is due to contraction. There are traces of a raised ridge round the papilla as in Perameles. Striated muscle-fibres terminate beneath the papilla?, as has been described in Phalangista and Halmaturus. This is also true of the anterior papilla?, which bend inwards and probably forwards as well (see fig. xv. Plate LIV., and compare with fig. XVIII.), so that they are bilaterally symmetrical taken together, but not singly. They are extremely different from the posterior papilla. There appear to be 5-8 tiers of bulbs. Nerve-cells can sometimes be detected in the nerves at the base of the papilla?. The relations of the striated muscle and the supporting framework of the papilla are as in Phalangista. B. Lateral Gustatory Organ.-The appearance, position, and ap- |
