1883.] TONGUES OF THE MARSUPIALS. 625 



upon an oval area surrounded by gland-ducts. Owing to the delicacy 

 of these terminal organs the area became protected by a fold round 

 its circumference in which all the bulbs except those of the central 

 line were sheltered. This is the stage represented in the figure, and 

 has not jjroeeeded further because the whole structure is additionallv 

 protected b} its position in the tongue, t. b. taste-bulbs, f. h. p. 

 Fine hair-like papilla? covering the posterior part of the organ. 

 f.h'.2>'- l^ine hair like papillse posterior to the bulb-bearing organ 

 and of different form from the others, gild. d. CTland-duct of serous 

 gland. 



Fig. XIII. X 145. Transverse section of the obliquely directed anterior bulb- 

 bearing ridge of OmUhorhi/nchun. gld. d. Dui-t of serous gland 

 opening into the narrow space between the ridge and the cavity in 

 which it is placed. The ridge is placed upon a very exposed part of 

 the tongue, and is therefore most exceptionally jjroteeted, being only 

 reached from the surface through a narrow chink (probal)ly closed by 

 a sphincter muscle). The necessity for this extreme protection is 

 probably to be found in the sti-ucture of the bulbs, which is very dif- 

 ferent from that of higher mammals. 



Fig. XIV. X 14-5. Vertical longitudinal section through the left anterior circum- 

 vallate papilla of HaliTuiturus valabatits. c. p. Coronate papilla. 

 The taste-bulbs {t. b.) are now of the norm.al marsupial tyjje (leading 

 up to those of the higher mammals, but showing traces of development 

 from the cells of an interpapillary process), and are probably less 

 sensitive than those of Orjiithorhynchiis, which are essentially sub- 

 epithelial. The apex of the papilla emerges from the cavity in which 

 most of it is placed, but the part thus exposed is not covered by taste- 

 bulbs, which are present over all the protected part (nearly the whole). 

 The apex is directed forwards and the symmetry is bUateral. It is 

 very likely that the mouth of the depression can be closed. 



Pig. XV. X 145. Vertical section through one of the anterior circumvaUate papillse 

 of Belidei's breviceps. The apex is directed inwards rather than 

 foi'wards, but the two papillae are bilaterally symmetrical together, if 

 not so individually. 



Fig. XVI. X 14-5. Vertical longitudinal section through one of the anterior 

 circumvaUate pa]:>illje of PhaJangista vulpina. The apex is directed 

 forwards, gld. Gland of which the ducts {gld. d.) are seen opening 

 into the space between the papilla and its cavity. 



Fig. xvii. x]4'5. Vertical section through the posterior circumvaUate papilla of 

 Belideus breviceps. It is likely that this papilla is radially symmetrical, 

 for the difference between the two sides is probably accidental. The 

 overhanging surface which bears the bulbs is a trace of the structure 

 shown in the preceding figures. Otherwise the shape resembles that 

 of the higher mammals. It is very interesting that the anterior and 

 posterior papillae of the same tongue should belong to such different 

 types (figs. XV. & xvii.). 



Fig. xvin. X 145. Vertical section through a circumvaUate papilla of Perameles 

 nasuta. Very similnr to the last, but symmetry decidedly radial. AU 

 the three papillae in this .si^ecies are of the same type. 



Fig. XIX. X 40. Horizontal section througli the depression (e. v. p. o.) leading 

 into the cavity containing the posterior circumvaUate papilla of Hal- 

 maiitrus iialabatits. The opening is surrounded by an irregular ring 

 of fine papilla; (r. /. 7;.) (not aggregated into 'coronate ijapiUse). 

 This section indicates tlie extreme narrowness of the opening into the 

 cavity. It is very probable that the mouth can be closed by a sphincter, 

 and that it is contracted in this instance. 



Fig. XX. x40. Vertical section through the posterior circumvaUate papiUa of 

 Phalangista vulpina. This papilla also belongs to the higher type, 

 while the anterior papilla of the same tongue is shown m fig. xvi. 

 Most of the references have been previously explained. g7i. c. Gan- 

 glion-cells arranged in groups at the lower part of a mass of nervous 



