162 BOTANICAL GAZETTE [aucust 
The flowers are small, greenish yellow, with short petals. 
They are quite shallow, the nectar being almost freely exposed. 
Nectar is secreted by five orange colored glands situated between 
the bases of the filaments. The staminate flowers have the 
petals a little longer and more often expanded, so that this form 
is the more conspicuous. The nectar glands are larger, more 
triangular ‘and united at base. The pistil is so strongly devel- 
oped that the flower appears to be perfect. In the pistillate 
flower the nectar glands are more bilobed. The stamens are 
of normal form, but greatly reduced in size, and are without 
pollen. Both forms are abundantly visited by insects. 
In the case of Xanthoxylum Americanum, which blooms from 
April 12th to 28th, and Ptelea trifoliata, blooming from May sth 
to June 12th, we have observed that the lists differ in the absence 
of the lower Aculeata from Xanthoxylum. This -was explained as@ 
result of the difference in their blooming time. If we compare &. 
Canadensis—April 4th to 27th—with R. glabra—June 8th to 24th 
—we find the same result. In the former case not one of thelowet 
Aculeata occurring on Ptelea flies while Xanthoxylum is in bloom. 
Here we have a similar condition, for Polistes metricus is the only 
one taken on X. glabra which is flying during the flower season of 2 
K. Canadensis. The large inflorescences of Ptelea and R, glabra - 
form more convenient resting places for these often large strad 
dling insects. The differences in the inflorescences May La 
accounted for partly by the difference in the composition of Re 
late insect fauna; but the early months, when there is apt ie : 
frost, are not favorable for the development of large ion“ 
clusters. Then, too, before the leaves appear, the smaller cae 
ters are sufficiently conspicuous. Other differences im the 
are connected with the blooming time, viz., the advent ; 
Prosopis, substitution of two late Colletes for the early C. inaeque’ 
and an increase of Halictus associated with the decline of the 
vernal species of Andrena. : os a 
ees following visitors of R. Canadensis were taken OF © 
4th, 1oth, 12th and roth: oe 
| : (2) Nowe 
HYMENOPTERA— A pide : (1) Ceratina tejonensis Cr., 45 
