612 MR. E. B. POULTON ON THE [DcC. 18, 



XVI. (Plate LIV.) rebpectively. Glands are very numerous (as they 

 seem to be in coimectiou with the circumvallate papillae of all Mar- 

 supials), as many as seven ducts being seen in one vertical section (of 

 an anterior jjapilla) ; they open at all levels into the involution (see 

 figs. XVI. and xx. Plate LIV.). Peripherally the serous glands are 

 replaced by mucous glands, although the latter are very abundant 

 and sometimes even enter the papillary body. The mucous glands 

 open upon the surface of the organ. In the larger posterior papilla 

 the central nervous mass is ganglion-like (as in Perameles, though 

 not to an equal extent), and nerve-cells occur high up in the papilla, 

 and in still greater abundance in an axial downward extension of the 

 central nervous tissues (see fig. xx. Plate LIV.). This condition 

 was not equally well marked (although present) in the incomplete 

 tongue ; and nerve-cells were not detected in any of the anterior 

 papillas, although they occur in nerves at the base and the downward 

 extensions are present. In all the papillae of both tongues the 

 dense mucosa beneath the epithelium of the involution is reflected 

 upwards into the papilla, and there forms a protective layer encircHng 

 the axial nervous mass (see fig. xx. Plate LIV.). In fact this 

 arrangement is exactly as in Halmaturus, with the same subepithelial 

 layer &c. (compare fig. xxi. Plate LV.). Striated muscles terminate 

 in the dense mucosa at the point at which it curves round to enter 

 the papilla (fig. xx. Plate LIV.). The various possibilities as to 

 the action of these muscles have been discussed (Halmaturus). Here 

 also it is possible that smooth muscle-fibres exist. 



The arguments apply with greater force to the anterior papillae, 

 for their shape at once suggests that the mouth of the involution can 

 be closed. 



There appear to be 1100-1200 bulbs to the square millimetre on 

 these papillae and the grooves of the lateral organ. 



The space between the papilla and its involution and the gland- 

 ducts were often filled with a deeply-staining coagulum in the in- 

 complete tongue ; it was probably a constituent of the secretion of 

 the serous glands acted upon by the hardening reagents. There 

 had also been a distinct discharge of a fluid substance from the 

 gustatory pores into this coagulum, in the form of small globules 

 often still connected with tlie pore by a narrow neck ; the globules 

 were distinct from the coagulum, as they remained unstained. 



The inferior convexities of the taste-bulbs are prominent and 

 distinct, without any of the filling-in between the bulbs that occurs 

 in higher animals. The bulbs stili resemble interpapillary pro- 

 cesses. The pores are very short. 



B. The Lateral Gustatonj Organ. — Vertical sections show that the 

 downward direction of the furrows is as irregular as their surface 

 view (see fig. xxxii. Plate LV.). The serous glands are very abun- 

 dant, opening at the bottom of the trenches. In one vertical 

 section three ducts were seen. At the sides the serous glands are 

 replaced by mucous glands which open freely on the surface, but 

 never, as far as I observed, into the furrows. Nerves are abundant, 

 and commonly contain nerve-cells collected in small ganglia ; they 



