48 - THE FERTILISATION OF FLOWERS. [PART II. 
Though the species of Prosopis are thus no better fitted for a 
floral diet than many Sand-wasps, they are of far greater import- 
ance as fertilisers on account of their more frequent visits to flowers, 
in procuring food for the young. We must consider minutely the 
form and action of their mouth-organs, to understand the higher 
HIT 
Jct 
" ies 
pt, 
ty 
i 
Hilti] 
(3 hi 
hs 
Hy 
iif 
wii é 
at ‘wisn 
ty, 
aT 
‘ 
Hiyittiel 
Ni} 
Fig. 11.—Mouth-parts of Prosopis. 
1.—Head with completely folded mouth-parts. Seen from below. ; ; 
2.—Front part of head, after the mandibles have diverged and the labrum turned upwards. ~ 
2b.—Mouth-parts in the same position; more highly magnified. 
3.—Mouth-parts, after elevation of the maxille, maxillary and labia! palps, and with the tongue 
partly extended; magnified as in 2b. 
Seb ja view of front region of head after complete extension of the mouth-parts; magnified 
as in 1 and 2, 
4b.—The completely extended mouth-parts; magnified as in 2b and 8. 
lbr, labrum ; ma, mandibles ; ¢, cardo; st, stipes; la, lamina; pm, maxillary palp ; mt, mentum ; 
li, ligula (tongue) ; pa, puraglosse ; pl, labial palp ; 0, eye. 
and more specialised forms of mouth in bees. When at rest (1, 
Fig. 11), the maxillz and Jabium in Prosopis are withdrawn into a 
cavity on the lower surface of the head, which they completely 
fill. They are retracted, not asin flies, by the contraction of a 
membranous piece into transverse folds, but by the folding up of 
stiff chitinous pieces jointed together, The two basal pieces or 
