1883.] TONGUES OF THE MARSUPIALS. 623 



toward that part of the figure which represents the anterior end of 

 the object depicted. 



Fig. II. Natural size. The right lateral organ and the adjacent structures of a 

 larger tongue of the same species (Haimaturws ucdabcUus), seen from 

 the side. The references are the same as those of the last figure. 



Fig. HI. Natural size. The posterior part of the left lateral organ, and the 

 adjacent structures of the tongue of the same species (Halmattirus 

 ualabatiis), seen from the side. In this specimen two of the smaller 

 elevations {gld. d.) are placed higher than the others, and thus conie 

 to be situated between the two posterior elevations of the lateral organ. 

 The same references. 



Fig. IV. Natural size. One of the three circumvaUate papillso (f. v. p.) of the 

 tongue of Halmatwrus ualabaius, seen from above. The arrangement 

 of these three papillffi is perfectly uniform in Marsupials as far as I 

 have observed ; i. e. at the angles of an isosceles triangle with the base 

 directed anteriorly. In this species the posterior papilla is situated 

 so far forward that it is placed between the other two, and the three 

 papillae are very nearly in the same straight line. The reference 

 mark points to the circular funnel-shaped depression leading to the 

 expanded cavity in which the large papilla is situated (see iig. xiv. for 

 vertical section of this structure). The sharp anteriorly directed apex 

 of the papilla is seen in the depression. Coronate jjapilliS cover the 

 surface round the deiDressiou, but they are less marked posteriorly. 



Fig. V. Natural size. The tip of the tongue of Macrojms melanojis, seen from 

 beneath. The papillate surface is seen to be continued on to the 

 inferior aspect of the tip, and there ends in an abrupt line against the 

 smooth epithelium. This line of demarcation is parallel with the 

 lateral and anterior contours of the organ. The fungiform papilla; 

 (f. 2^-) are unusually abundant and very variable in size : they are in 

 the usual situation, i. e. on the papillate side of the above-mentioned 

 line of demarcation. Their function is probably tactile, and they are 

 scattered among the coronate papillae, r. Ridge in the middle line 

 of the inferior surface of the anterior part of the organ : very constant 

 in Marsupials ; it is bordered on each side by a groove (</'".). The 

 ridge is usually sliarper and the grooves deeper than in this specimen. 



Fig. VI. Half natural size. The tongue of Maoroptis melanops, seen from above. 

 Ep. Epiglottis. The walls of the cavity have been held open by a 

 needle, shown in the drawing. The reference mark {c. v. pi.) points 

 to the depression leading into the left anterior circumvaUate papilla. 

 The structure is very similar to that of Halmaturiis. The lateral 

 filiform papillae {l.f- p.) and the lateral organ il.g. o.) occujjy very 

 nearly the same position that they have in Halmaturus. Only the 

 posterior parts can be seen from tliis point of view. They are better 

 shown in the next figure, r' Median raphe, well marked anteriorlj', 

 disappearing posteriorly at about the middle of the length of the organ. 

 Almost the whole of the surface represented is covered with coronate 

 papiUse. 



Fig. VII. Natural size. The left lateral organ and adjacent structures of the 

 tongue of Macropus melanops, seen from the side. The filiform 

 papillas have the usual structure and arrangement ; anteriorly and 

 superiorly to them the surface is covered with coronate papillae. The 

 lateral organ (/. g. o.) still takes the form of a series of slight elevations 

 with slit-like depressions on their summits. The series forms a very 

 perfect arc, and the regular arrangement (together with the whole 

 structure) shows a decided advance upon the condition of this organ 

 in Halinaturus, although a close relation with the latter is obvious. 

 It forms tlie first transition towards the more complex lateral organ. 



Fig. VIII. Natural size. The back part of the tongue of Phalangista vidpina, 

 seen from above. The lateral gustatory organ {I. g. o.) shows a great 

 advance upon that represented in the last figure. (For other aspects 

 of the lateral organ of Phalangista see the next flgui-e and fig. xxxii. 



41* 



