1893 NOTES AND COMMENTS. 323 



of the egg just below the stigma explains the remarkable symmetry 

 of most of the fertihsed pistils, contrasting with the constriction 

 or indentation of the Eastern species at the point where the ovary 

 has been punctured. 



In another smaller species, Yucca data, observed at Eagle Flat, 

 Texas, Pronuba yuccasdla was the agent of pollination. When about 

 to deposit an eg^, the moth, as in Y. filamentosa, runs nervously about 

 within the bottom of the flower, then scrambles to the top of the 

 pistil and backs down between two stamens by a succession of jerks, 

 until her head is about level with the base of the style. Clinging to 

 the pistil, she then punctures the ovary, and the egg is consigned to 

 its place in the manner so well described by Riley for filamentosa. 

 Usually each oviposition is followed by pollination, but in a few 

 cases two eggs were laid before pollen was carried to the stigma, and 

 sometimes so disturbed is the moth by the bright light of the 

 observer's lantern, that she will leave a flower altogether without 

 polHnation. In one such instance her first act on entering another 

 flower was to thrust her pollen-laden tentacles into the stigma, though 

 it is unusual for this to precede oviposition. On several occasions, 

 when disturbed in laying her egg, the moth ran upon a stamen, 

 shaking it quite violently and making several passes at the anther 

 with her tentacles, as if frightened from one of her occupations only 

 to engage in another. The very distinct Californian Yucca Whipplei, 

 as Professor Riley has shown, is pollinated by a distinct Pronuba, 

 which he names P. maculata, of a general white colour, but mottled 

 with black. In this species the pollen is not loose and powdery, as 

 in Yucca proper, but glutinous, and frequent observation has shown 

 that it may be deposited on the stigma directly from the anthers in 

 closing flowers, so that self-pollination becomes possible, and Mr. 

 Coquillet, of Los Angeles, records the seeding, in 1892, of a number 

 of panicles which he had covered with gauze before any of the flowers 

 opened. Owing to the more open and more diurnal character of the 

 flowers in this species, the moth is far more active in the daytime than 

 its congeners. Moreover, the resting position, with the head towards 

 the stigma, is almost identical with that taken in oviposition, which, 

 like pollination, may be witnessed at any time during the day. 

 Standing on the side of the pistil the female pierces the ovary at the 

 thinnest part. Generally not more than six eggs are laid in one 

 pistil — one on either side of each septum — often fewer, so that even 

 if they all hatch — an unlikely event — there is rarely more than one 

 larva to each tier of seeds, thus allowing a fair percentage to ripen. 

 Pollination was well seen in the variety gvaminifolia, where it was 

 observed several times under a cloudless sky, the first time at about 

 noon. Flying into a flower, the moth runs about the bases of the 

 stamens in the usual way, then quickly clambers upon the inner side 

 of a filament, and, with the tentacles stretched over the pollen masses, 

 drags first one and then the other out of the anther cells, pressing 



Y2 



