77 
are flies, which do not depend on floral diet exchisively and are 
not to be regarded as anthophilous insects. 
The two remaining species of Diptera (Gonia capitata, De G. 
and Siphona geniculata, De G.) belong to the Tachinidae, a family 
well known from the fact that the larvae of all of the species live 
parasitically on other insects, while the adult flies generally obtain 
their food from flowers. 
After the blooming period of Erigenia has fairly begun, the 
bees appear among the other visitors. The honey bee is frequently 
observed on the flowers, and the remaining two bees on the list 
are species of Hal ictus, a very important genus belonging to the 
Andrenidae, a family comprising all oi our short-tongued or less 
specialized bees. 
In Southern Illinois, where Erigenia bnlbosa seems to be more 
abundant, and where, on the first warm days of spring, the 
climatic conditions seem to bring out a more numerous set of 
visiting insects than in our vicinity, Robertson (5) has taken a 
larger percentage of bees on this species, than on any of the other 
species of Umbelliferae observed by him. 
By reviewing the results obtained, we are led to the conclusion 
that Trillium nivale, Riddell, and Erigenia bulbosa, Nutt. do not 
interfere with each other as regards their mode of pollination, 
Trilliuni nivale not relying on the visits of insects, but resorting 
to spontaneous self-pollination, Erigenia bulbosa on the contrary 
furnishing a well-defined case of proterogyny and securing cross- 
pollination through insect agency. 
The small size of both plants is remarkable, wdien compared 
with that of near related forms. The position of the flowers in 
close proximity to the ground and among fallen leaves and dry 
grass, undoubtedly affords protection from the ill effects of frosty 
weather, and reminds one of the small sized species growing in 
high altitudes and having to endure low temperatures even during 
the nights of summer, as for example Alpine plants. Rocky Moun- 
tain plants, etc. Both our species occur in open woodlands, as is 
the rule with our vernal species of herbaceous plants. Blooming 
so early in the season, as they do, their small size is of no dis- 
advantage to them ; later on, plants of such dwarf-like appearance 
could not inhabit the same locality, without being concealed 
beneath a luxuriant growth of other herbaceous plants of greater 
size. 
The first open flowers on the catkins of our willow species — 
Salix discolor, MuhL, appear in the second or third week in April, 
(5) C Robertson. Flowers and Insects. Umbelliferae. Trans. Acad. Sc. St. Louis, Vol. 
V, pp. 450-451. 
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