No.423.] MORTHERN POLYPETALOUS FLOWERS. 215 
purple spots, which on the third day fade entirely away, leaving 
the flowers bright yellow. The colors of the flowers of the 
Crassulaceze are often correlated with the colors of the stems 
and leaves. 
The flowers of the Saxifragaceze are small and arranged in 
racemes, cymes, and panicles, or solitary in Parnassia. The honey 
in most species is easily accessible, and the visitors are chiefly 
flies, which appear to have influenced the development of the 
coloring, To these insects white and yellow, marked or dotted 
with yellow, red, or purple, are thought to be especially attractive. 
The relation of Diptera to the flowers of Saxifraga is shown in 
the accompanying table compiled from Miiller and Knuth. 


















i SI ed Dır- | Hymenop-| Co reop- LEPIDOP- Wena: 
: x TERA. TERA. TERA. TERA. e 
S. rotundifolia .| White .....| 14 I — de 15 
S elles. ey White La is 12 2 I I 16 
S. aspera | White ....:. 2 — m Po 2 
S oye ...|IwHe..... 9 2 2 on 13 
Sater i  ) White ss. 65 II 5 10 9t 
d ME Hee ass Whit V. ay 15 3 3 3 24 
A eerie. ...| Wie s 4 I — — 5 
a ’ 
SS. muscoides . . | Greenish yellow 6 I I I 9 
w” 
S. aizoides. . . . | Golden yellow .| 85 20 8 13 126 
-— 
S. oppositifolia .| Purple ..... 4 = I 3 8 
ee 216 41 mr -a.T 
ak a TÉ 

The genus Saxifraga is highly interesting because of the 
colored dots upon the corolla of many of the species. The white 
corolla of S. rotundifolia is sprinkled with round dots, the outer - 
