Robertson — Flowers and Insects. 439 
crataegi Rob. 2, c. p.; (7) Halictus pectoralis Sm. 9, c. p.; (8) H. fasciatus 
Nyl. 9, c. p.; (9) H. stultus Cr. 9, c. p. 
Diptera — pide: (10) Empis distans Lw., s.; Syrphidae: (11) Syritta 
pipiens L., 
Geum atpum Gmelin.—The stems grow about six deci- 
metres high and bear scattered flowers, which have white 
petals and expand 18 or 20 millimetres. 
The flowers are proterogynous. The outer anthers dehisce 
first. There is abundant opportunity for cross-pollination. 
Later, self-pollination by insect aid is possible. In case 
insects fail, the lower stigmas may receive pollen from the 
neighboring anthers. 
Nectar is secreted by the portion of the disc on which the 
stamens are inserted. 
The flowers are visited by small Hymenoptera and Diptera. 
I have noted them in bloom from June 20 to September 13. 
The insects mentioned in the following list were noted on the 
flowers on July 6 and 11: — 
Hyme silaceviiten dee (1) Phileremus illinoensis Rob. 9, s.; (2) Cal- 
‘mae andreniformis Sm. ,j',s.; Andrenidae: (3) Halictus se ost Nyl. 3, 
3 (4) H. thonee tes D) 83 (5) H. pruinosus Rob. 9, s. and c. p.; (6) H 
“eee Sm. 9, s. and c. p.; (7) H. tegularis Rob. 9, s.; ee H. stultas 
Cr. 2, s.and c. p.; (9) Augochlora similis Rob. 3'9, s. and c. p.; (10) Pro- 
sopis pygmaea Cr. 4, s.; Eumenidae: (11) Eumenes fraternus Say, s.; (12 
and 13) Odynerus spp., s.; Crabronidae: (14) Crabro interruptus Lep., s.; 
rat St Cerceris compacta Cr., s.; Chrysididae: (16) Hedychrum 
orate Brul ¥ 
tera es pats : (17) Mesograpta marginata cmd 8.3; Tachinidae: 
a8) Olypsees 8p., 8.3 percipightiee (19) Sarcophaga sp., 8 
Coleoptera — Cer erambycida: ~ Euderces picipes F., s.; Mordellidae: 
(21) Mordella marginata M. 
Hemiptera — Corkiictaeiait (22) Corimelaena pulicaria Germ., 8s. 
Geum vernum Torr. & Gr. —A few stems from the same 
base rise three or four decimetres in height and bear small 
cymes of yellow flowers. 
The flowers expand about six or seven millimetres, the 
petals, however, being quite small and inconspicuous. The 
concavity of the receptacular tube is filled by a globular head 
of pistils, Above, it is produced into a thin, many-lobed rim 
Which separates the head of pistils from the stamens. The 
filaments are inserted in a groove lying between this rim and 
