177 
INTERNAL ORGANS OF THE LABELLA 
These consist of seven different organs and are bilaterally 
symmetrical (fig. 8). 
(1) The Teeth (j in all the figs.). There are five of these and a 
small accessory or rudimentary' one. They are relatively very large, 
the length of an individual tooth being equal to about one-fourth the 
entire depth of the labellum. They are articulated to an extremely 
flexible, narrow plate, which is in turn articulated to the true plate of 
the labellum. The first (proximal) and second tooth have each a 
strong lateral process (tooth) on the lateral proximal margin, 
and the tips of each are serrated on both sides ; the 
three succeeding teeth are similar in structure, but the lateral 
deep dentitions are now on the opposite sides. In the 
everted position the te£th are freely exposed, widely divergent, and 
project at right angles and even backwards and dorsalwards. It is 
evident from their position and extent of motion that they act as the 
chief and, in fact, the only cutting organs of the proboscis. 
(2) I HE PETIOLATED Blades (/ in all the figs.). These are 
long, curved, blade-like organs covered with minute hairs on the 
ventral concave surface. All are attached to long and extremely 
slender stalks arising from strongly chitinised projections of the 
narrow tooth plate. They arc grouped in the following order: At 
the proximal extremity, exterior to the tooth, are two groups ; the first 
consists of two or three very small blades attached to a relatively 
strong branched stalk; the second group consists of seven or eight 
blades, some of which arc scarcely larger than those of the first set; 
the main stem in also stout, but the lateral stalks carrying the blades 
are extremely slender. Between each tooth is a set of four blades 
auanged in two pairs, the blades of each pair being widely separated, 
so that they resemble, somewhat, the arms of a lyre ; the blades 
partly overlap, but the tips of the lower pair extend considerably 
beyond the upper pair, and when the labella are closed they reach as 
far as the basal row of external squamae fonning the extreme edge of 
the labella (fig. 10, in dotted lines). Anterior to the last (fifth) tooth 
aie three more sets of blades; the first set (between the fifth and the 
accessory tooth) consists of six or seven blades ; the second of a 
similar number, and the third of four or five, of which three resemble 
