436 Trans. Acad. Sci. of St. Louis. 
(4) A. cressonii Rob. ,j', 8.; (5) A. flavoclypeata Sm. ,j', s., freq.; (6) Halic- 
tus lerouxii Lep. 9, s.; (7) H. zephyrus Sm. 9, s.; (8) H. confusus Sm. @, 
s.andc. p.; (9) H. stultus Cr. 9, s.; (10) Colletes inaequalis Bis 
Diptera — Bombylidae: (11) Bombylius major L. s.; Syrp : (12) 
Chrysogaster nitida Wd.; (18) C. ustulata Lw.; (14) Pintyohicas sas 
Staeg.; (15) Syrphus americanus Wd.; (16) S. ribesii L.; (17) Mesograpta 
geminata Say; (18) Sphaerophoria cylindrica Say; (19) Eristalis dimidiatus 
Wd.; (20) Helophilus similis Mcq.; (21) Brachypalpus frontosus Lw.— 
all f. p. and sometimes s.; Tachinidae: Gd) Gonia frontosa Say, s.; Rabies 
gidae: (23) erg he sp., 8.; Muscidae: (24) Lucilia c ot 25) L. 
Scie =i ; Cordylur cond (26) Scatophaga squalida Mg. 
pidoptera — Nymphalidae: (27) any atalanta L.; “ae = huntera 
F.; ro A eh (29) Piusia aiiee Gn.; (30) sp.—all sucking. 
: Galtopberai: Chrysomelidae: (31) Guasdecacs atra Ahr., f. p. 
Prunus srrotina Ehrh.— The trees are filled with small 
racemes which bear numerous small white flowers. The 
flowers measure about eight millimetres across. When they 
open, the stigma, which is already receptive, exposes its. 
broad surface above the anthers, which are still closed and 
are held down by the incurved stamens. Later the stamens 
turn outwards and discharge their pollen. Flowers which 
are imperfectly expanded show the anthers discharging their 
pollen so near to the stigma that self-pollination is insured. 
The receptacular tube forms a shallow cup, the inner wall of 
which secretes nectar. The nectar is readily accessible to 
short-lipped insects, the style and stamens forming a very 
trivial obstruction in the way of the guests. 
This species blooms later than P. americana, April 25 - 
May 23, and has more exposed nectar. Its visitors are like 
those of Crgtaegus. May 7, 13, and 18, I noted as visitors :— 
Hymenoptera — Apidae: (1) Apis —o L. 8,8. andc. p.,ab.; (2) Bom- 
bus americanorum F. 9, s., freq ; (3) B. virginicus Oliv. 9,s.; (4) B. 
separatus Cr. 9, 8.; (5) Synhalonia specioas Cr. g', 8.; (6) Ceratina tejonen- 
ed has 6» 8.; (7) Nomada sayi Rob. 9, s.; Andrenidae: (8) Andrena pruni 
De Y, 8 and c. p., freq.; (9) A. sayi Rob. OF i and c. p.; (10) A. cressonii 
9,8. and c. p., freq.; (11) A. maineba ctate Sm. ¢,s.and c. p., ab.; 
(12) A. nuda, Rob. 9, 8, and c. p.; (18) A. rugosa Rob. <j’, s.; (14) A. for- 
besii Rob. 9, 8. and c. p.; (15) A. anyenie Rob. 9, s. and c. p., freq.; 
(16) A. crataegi Rob. ¢', s.; (17) Halictus coriaceus Sm. Q, 8., freq.; (18) 
lerouxii Lep. 9, s. and c. p., freq.; (19) H. fasciatus Nyl. 9, s. and c. 
-; (20) H. pilosus Sm. 9, s. and c. p.; (21) H. cressonii Rob. Q, 8. and c. 
o (22) H. zephyrus Sm. Q, s. andc. p.; wae H. confusus Sm. Q, s. and 
C. p., freq.; (24) H. stultus Cr. 9, s. and c¢. p., freq.; (25) Apawcemti 
radiatus Say 9, s.; (26) Augochlora iecaaks Q, 8.; (27) A. similis 
