1895.) The Philosophy of Flower Seasons. 107 
14, Plate VIII) with their numerous stamens are the particular 
favorites of the less specialized bees, and it would be fairly 
impossible for them to be so efficiently attended late in the 
season. No flowers are more convenient for the imper- 
fectly adapted flower insects than those of the parsley family 
(Umbelliferae, Fig. 18, Plate VIII). While the later blooming 
species are visited by a more numerous set of insects, the 
visitors are less efficient. . The flowers are somewhat neglected 
by the higher bees (Apidae, Fig. 27, Plate IX.—2 spp. per mm.). 
so that in order to secure the most useful set of visitors it 
is desirable to bloom early, under the maximum of the An- 
drenidae. I have shown that the harbinger of spring (Eri- 
genia), the earliest spring flower, has a larger percentage of bees 
among its visitors than any other plant of the family,and that 
the early blooming species with simply concealed nectar show 
more bees as visitors than those with deep-seated nectar but 
blooming late. On consulting the curves for bees (24) and 
other Aculeate Hymenoptera (25) and flies (22), it will be ob- 
served that early in the season the predominant insects are 
bees and flies, so that by early blooming the less specialized 
flowers gain an advantage similar to that secured by the more 
highly specialized in a later season in concealing their nectar, 
i. e. they acquire a higher proportion of the more efficient 
flower insects. The pond lilies (Nymphaeaceae) come in bloom 
late, probably on account of their aquatic habitat and have a 
long period, probably on account of occupying a position free 
from the competition of overshadowing form, but they are 
pollinated by late-flying bees and flower flies; and I have 
named two species of bees (Halictus nelumbonis and Prosopis 
nelumbonis) on account of their close economic relation to 
these flowers. The violets (Fig. 16, Plate VIII) are spring 
fiowers, there being no normal late-blooming indigenous spe- 
cies. Those with the lateral petals bearded are adapted to 
the mason bees (Osmia, Fig. 31, Plate IX), small greenish 
species with pollen-collecting brushes on the ventral surface 
of the abdomen, which fly early apparently to avoid compe- 
tition with the large allied genus of leaf-cutter bees (Mega- 
chile, Fig. 32, Plate IX). When visiting the violets these 
