1896] FLOWERS AND INSECTS 157 
ide: (12) Odynerus albophaleratus Sauss.; Crabronide: (13) Oxybelus 
4-notatus Say; Philanthid@ : (14) Cerceris pedalis Cr. 
COLEOPTERA—Coccineliide : (15) Analia bipunctata L.; Dermestida : (16 
Anthrenus scrophularie L.; Lampyride@ : (17) Chauliognathus pennsylvanicus 
De G.; and other insects which I have not seen, probably flies. 
On the literature of Ptelea see: 
(1) Hildebrand, Geschlechtsvertheilung bei den Pflanzen, 11:26. 1867. 
—(2) Urban, Zur Biologie und Morphologie der Rutaceen, Jahrb. bot. Gartens 
Berlin 2:397-8. 1883. (Just 11°: 497.)—(3) Kerner, Pflanzenleben 2: 295. 
1891. (Just 18" :486.) 
Ruamnus L.—The species which have been studied are 
dicecious — R, cathartica (Darwin 7), saxatilis and tinctorta (Ker- 
ner 19)—-or with flowers perfect, as in R. Frangula and pumila 
(Miller 3, 11), the former being proterandrous and the latter 
homogamous. R. cathartica has four sub-forms (Darwin 7), 
and Frangula shows a tendency to produce a long and short- 
styled form, as in our R. lanceolata (Schulz 17). 
The flowers are small, greenish, with easily accessible nectar 
and have been considered to be adapted to flies (Delpino 5, 
Miiller 12, 13), but this does not seem to be supported by suf- 
Stient data:. Sell. more extreme is the limitation of the proper 
Visitors to flesh-flies (Kerner 19). My list of visitors of R. /an- 
ceolata resembles those of white or yellow flowers with similarly 
placed nectar and blooming about the same time. The results 
of the observation of different species in separate regions is 
given in the following table: 
Apide Andrenida Other Hymenop Diptera Coleoptera Total 
Rhamnus lanceolata, Illi- | 
ink oe 
2% 2 22 Ce 
- Frangula, Low iser-) : 
many, Miiller (3, in} f : : : : 
- Frangula, Flanders 
MacLeod (20), .- 
R. pumila, A] it 
Oa. ce Sa : : 
. RHAMNUS _LANCEOLATA Pursh.— According to Darwin (7), 
this species is dimorphous, but not properly heterostyled. The 
small trees grow as high as three or four meters and bear 
