PREAISTORIC BOTANISTS. 143 
botanical sequence, and certain affinities are readily traceable be- 
tween the two orders, both plants having milky sap, opposite, 
entire leaves, long pods, silky seeds, and other more intricate 
resemblances. Looking a little further into the subject, we find, 
moreover, that while now separated in classification, the earlier 
botanists had included the plant with the milk-weeds, from which 
it was withdrawn only after much scholarly discussion. Clearly, 
the antecedent classification of the butterfly should have been re- 
spected at the hands of the learned disputants. The dog-bane 
was linked with the milk-weed eons before the world knew a 
human botanist. When the writer's botany appears, this priority 
of Danais Archippus, Ph.D., D.D., F.D.S., will be duly recognized. 
I have never seen this caterpillar on the closely allied peri- 
winkle, but would almost expect to find it there even as I once 
observed the butterfly suggestively hovering about a vine of 
Hoya or wax-plant, a cultivated exotic trained about a porch, 
but which is a true relative of the milk-weed. 
A somewhat parallel instance of botanical priority is to be 
seen in the Parnassus Apollo butterfly, the beautiful sylph of the 
Swiss Alps, member of a boreal tribe, rarely found below an ele- 
vation of 1500 feet—lovers of the mountains, as their name im- 
plies, and one of which, pictured at the right of my Alpen de- 
sign, I observed among the Alpine cowslips on the summit of 
Righi Culm. The food plant of this insect, according to the 
authorities, is confined to the saxifrages, a tribe of plants com- 
prising a large number of Alpine species. I learn, also, that the 
caterpillars are sometimes found on a species of sedum—a stone- 
crop—two families distinctly separated in the botanies, though 
following each other in Gray’s sequence; and research further 
shows that De Candolle originally traced the closest affinity be- 
tween these two orders. It is not on record whether Apollo gave 
him the hint. This airy butterfly is common alike in the flow- 
ery vales and snowy heights of Switzerland, doubtless finding 
abundant congenial companions among this genus of Alpine 
plants (Saxifrages), which have accompanied the surface drifts and 
hugged the skirts of the glacier through the ages, many of which, 
