No. I.] OBSERVATIONS ON THE GUSTATORY ORGANS. yi 



itive than those of Perameles, Phascolontys, and Didelphys, 

 but are further advanced than in Halmatnrus, Mao'optis, and 

 Belideiis. They approach quite closely Phascolarctos, Bettongia, 

 and Phalangista. The general surface adjacent to the gustatory 

 triangle is quite papillate. The posterior papilla is small, but 

 clearly defined, and measures 0.85 mm. at the widest part. The 

 anterior pair are elongated and deeply sunk, and their bases are 

 slightly constricted. They measure 0.55 to 0.80 mm. trans- 

 versely, and are 0.90 mm. in height. The trenches encircling 

 them are uniformly narrow, their walls converging above, leav- 

 ing only a narrow opening, in which the apex of the papilla is 

 visible. Serous glands and ducts are fairly plentiful, the latter 

 opening into the trenches at their deeper part. The results 

 of Poulton's researches {Proc. Zool. Soc, 1883, p. 609) on the 

 tongue of Pctrogale xantJiopiis are in some respects quite dif- 

 ferent from mine. He says : " The whole tongue is strikingly 

 similar to Macropus, and, like it, follows the type of Halmatnrus. 

 The circumvallate papillae are arranged in a similar triangle (the 

 posterior angle being very obtuse), and nothing can be seen 

 from the surface except the orifices of the involutions. The 

 posterior papilla appears to be rather different from the anterior, 

 the entrance being extremely small (probably contracted), and 

 lies in the centre of a raised subcircular area, of which the sur- 

 face is smooth. The anterior openings are larger (probably less 

 contracted), and the raised area is less distinct." The variations 

 in the papillae of these two species of a common genus are cer- 

 tainly as marked as those which obtain between some species 

 of different genera. The taste-bulbs of the posterior papilla are 

 confined to its lateral area. They are disposed in several tiers, 

 the mean number in a tier being eighty-five. They are closely 

 set and remarkably uniform in size, measuring 0.060 mm. in 

 length and 0.029 mm. in breadth. Non-medullated nerves and 

 groups of small ganglia are present in the axial region of the 

 papilla. The anterior papillae bear bulbs on their summits as 

 well as upon their lateral area. In the latter region there appear 

 to be upwards of twenty tiers of them. 



The Lateral Gustatory Organs. — These organs measure 4.50 

 mm. in length and 0.55 mm. in breadth. Each consists of five 

 fairly regular folds, bearing bulbs on their lateral area. The 

 furrows separating the folds are narrow, and average about 0.55 



