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Show 616 MR. E. B. POULTON ON THE [Dec 18, tween the anterior and posterior circumvallate papilla?. The posterior is very large and shows perfect radial symmetry, exactly resembling the ordinary papilla? of higher mammals as seen from the surface; it is placed some distance behind the anterior papilla?, as in Belideus & c The anterior papilla? are small, but quite distinguishable from above; they seem to retain very little (if any) bilateral symmetry and forward direction. To be certain on this point, sections are necessary. The great development of the posterior papilla? in Marsupials, where there is any difference between the three, compares in an interesting manner with the condition of many higher mammals. In these latter it is quite common (e. g. in many Insectivora &c, &c.) for the posterior papilla of the triangle to be altogether lost, and for the tongue only to possess two papilla? on the same level; these two obviously represent the anterior papilla?, for in allied species (e.g. the Hedgehog among Insectivora) the triangle is complete. The three circumvallate papillae of Acrobates are placed on a depressed smooth area at the back of the tongue. Immediately anterior to the two foremost papilla? the coronate surface begins with a sudden transverse rise right across the tongue, thus sheltering the circumvallate structures. There is a distinct normally placed lateral organ beneath the filiform papilla?, which is interesting in its possession of only two furrows (as far as I can tell from surface examination); these are distinct and well developed, and surrounded by prominent lips. The coronate papilla? are as abundant as usual and have the ordinary arrangement. Fungiform papilia? are very common on the upper surface as well as on the sides. On the underside of the free part the ridge and grooves are normal. The pointed tip of the organ is not turned down, suggesting that the figure of Belideus (fig. x. Plate LIV.) is correct. It is extremely interesting that (as in the young marsupials and in Cetacea) the epiglottis can be made to protrude through a notch in the soft palate, so that breathing can go on uninterruptedly during the time that the animal is drinking the sweet juices of the flowers of Eucalypti, which constitute its food. The epiglottis is long and tubular, and its opening is prolonged into a slit posteriorly, so that it must be a great protection at all times, and a perfect protection when it is thrust through the notch, as I found it in this specimen. The soft palate is continuous with the pharynx laterally for a long distance backwards; its free edge is a deep mesial notch, of which the anterior convex edge is just over the tubular epiglottis, and of a size and shape that the latter fits completely. The fluids (as in other cases) must pass on each side of the epiglottis. This tongue obviously belongs to the Phalangista and Belideus type, and is a more complete specialization in the same direction than is met with in these latter. THE TONGUE OF Perameles nasuta. I have already described the general appearance and histological details of this tongue in the ' Quarterly Journal of Microscopical |
