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Show 1883.] APPARATUS OF THE TENUIROSTRES. 65 and as they likewise slightly curl up, two secondary tubes, more or less completely closed, are formed. Further in front, these median edges become laciniated in various ways. Towards the tip of the tubes the greater portion of the thin lamella constituting them splits up into bristles ; but the outer edge seems to remain intact. The mode of splitting up, or the shape of these lacinise, vibrissa?, or bristles of the median parts of the tubes seems to be characteristic of the different species, and even of the genera. The drawings of these delicate parts (Plate XVI. figs. 8-10) will explain their shape and formation much better than any amount of description. W e meet with a similar but much more complicated formation in the tongue of the Meliphagince. Their os entoglossum ends in two cartilaginous filaments ; and the whole tongue shows a truly dichotomous arrangement, which towards the tip leads to the formation of the well-known " brush." The second drawing exhibited (fig. 2, p. 65) shows a series of sections through the tongue of Ptilotis carunculata. Stage A corresponds with that in Cinnyris; but in the next stage we see that the median unpaired and the two lateral inwardly Sections of the tongue of Ptilotis carunculata. directed outgrowths of the ventral sheath are much stronger than in the corresponding regions of the tongue of Cinnyris. In stage C the approaching separation into a right and left half is indicated by a deep fissure/, and we observe similar fissures in the two lateral outgrowths (g and h). The lateral horns (I) of the ventral sheath do not become reduced, but are preserved; and the dorsal sheath (d) forms a thin and only half-cornified lining to the cavity or open groove on the upper side of the tongue. In front of this section, corresponding to the level D in fig. 2, the separation into a right and left half is complete, and the remnants of the dorsal sheath are seen in a similar position to that which they occupy in fig. 1 D, in Cinnyris. PROC. ZOOL. Soc-1883, No. V. 5 Fig. 2. D E |
