coo 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 tliree are present, 

 arranged in an isosceles triangle (universal in ]\Iarsupials). 



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 fili- 

 form 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 mm. 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 com- 

 plete 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., iii. 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 the 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 



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