614 MR. E. B. POULTON ON THE [DeC. 18, 



the possession of two anterior circumvallate papillfe, following Hal- 

 maturus, and a posterior papilla much resembling that of higher 

 animals. 



The Tongue of Belideus breviceps. 



This specimen had been preserved in spirit, and although unsuit- 

 able for minute work I was able to make out a great many interest- 

 ing 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 Acrohates bears out this view. The 

 posterior circumvallate papilla is large and radially symmetrical, 

 showing a large circular area on the surface ; the two anterior 

 papillae are not radially symmetrical, and are nearly hidden from 

 view in narrow, slit-like, oblique depressions. Thus the arrange- 

 ment 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 papillae, 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 

 II mm. long. There is a sharp inferior median ridge with the two 

 grooves. 



Minute Structure. — I. Gustatory Structures. 



A. Circumvallate Papillce. — The posterior papilla resembles that 

 of Perameles in possessing a ganglion within it, which is not pro- 

 longed 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 con- 

 traction. 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 Halmuturus. This is also 

 true of the anterior papillae, which bend inwards and probably for- 

 wards 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 papillae. 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- 



