| OCR Text |
Show 600 MR. E. B. POULTON ON THE [Dec. 18, surface of the tongue, always sheltered by a trench, and sometimes very completely protected. Gustatory. Posterior angle.-The angle made by the posterior circumvallate papilla with the two anterior papillae, when only three are present, arranged in an isosceles triangle (universal in Marsupials). Lateral gustatory organ or lateral organ.-Used in its old sense. The term foliate organ or papilla foliata is misleading in directing the attention to the ridges instead of to the grooves (which are primary). Gustatory. Fungiform papilla.-In its old sense, except that it should not be used for the circumvallate papilla. The latter is primarily gustatory, the former primarily, and perhaps ultimately, tactile. Filiform papilla.-The old sense. It may be either mechanical or tactile. Its papillary process bears secondary processes. Hair-like papilla.-A very fine filiform papilla of which the papillary process does not bear secondary processes. Mechanical. Coronate papilla.-A compound filiform papilla ; the summit being crowned by a ring of recurved hair-like papillae. Mechanical. Characteristic of Marsupials. Fasciculate papilla.-A convenient term for the compound filiform papilla in which the secondary papillae are not arranged in a circle, but brush-like. Mechanical. I will now proceed to describe the tongues, beginning with those that least resemble this organ in higher mammals, and gradually working upwards. THE TONGUE OF Halmaturus ualabatus. The material consisted of the back part of one tongue, the lateral gustatory organs of others, and the part containing a circumvallate papilla. All these had been hardened in chromic acid and were in excellent condition. General description.-The smaller tongue was 27*5 m m . in width posteriorly (although there was some distortion due to cuts permitting the entrance of the hardening fluids) ; the other dimensions are shown in fig. i. Plate LIV., and from this also the size of the complete organ is suggested. The upper surface is densely crowded with large coronate papillae, between which, just above the smooth lateral surface, a few fungiform papillae of normal appearance are scattered. The lateral gustatory organ is in the form of a series of mound-like elevations (about six in number), placed just below the posterior part of the side of the papillate surface (see figs, i., II., in. Plate LIV.). At the summit of each elevation an elongated (sometimes circular) depression is situated like a crater. The whole appearance suggests a series of gland-ducts; and this view of tbe origin of the lateral gustatory organ is confirmed by a study of the minute structure. Below these elevations there is a less regular, longer row of smaller depressions sometimes situated upon mounds, but in some cases only surrounded by slightly raised rings. These structures extend for some distance in front of the former (and often to some extent |
