734 On the Natural Succession of the Dicotyledons. [ November, 
Very little more than this can at present be predicted with 
regard to what the true “Natural System” really is, which we 
are still so far from understanding; but it would seem from the 
peculiar character of Composite, and especially from the double 
safeguard of their narrowly tubular corollas, their epigynous 
calyx (pappus), and syngenesious anthers, still further secured by 
the massing of the flowers into dense heads, that this order, which 
is also the largest in the vegetable kingdom, should be regarded 
as the highest and most specialized family of plants, and might 
be fitly made to crown the natural system. 
The general arrangement above outlined is further substan- 
tiated by the limited data which paleontology affords. The 
greater part of the fossil plants of this class have been found in 
the Cretaceous formation. They nearly all belong to the apet- 
alous and polypetalous Divisions, but by far the greater number to 
the former; such genera as Salix, Quercus, Platanus, Sassafras, 
etc., occur most frequently, and some of these have been traced 
to the lowest Cretaceous strata if not to the Jura. That they 
existed in still earlier times can scarcely be doubted, and high 
authorities have fixed upon the Trias as the probable epoch in 
which the earliest dicotyledonous genera made their appearance. 
In the Upper Cretaceous certain polypetalous genera begin to 
be found, among which are numbered Magnolia, Liriodendron, 
Prunus and other multi-staminate plants, most of which have been 
assigned a high rank in the current system. This fact and others 
seem rather to indicate that a great many stamens and an elon- 
gated receptacle are marks of a low organization, as if just 
emerging from the catkin-stage. Very few gamopetalous plants 
are found fossil, strongly implying that they belong to late 
Tertiary periods. Especially significant is the absence of those 
having elongated tubular corollas, while it is believed that the first 
fossil Composite plant is yet to be discovered. 
_ Little, therefore, as is really known of the natural succession and 
actual genealogy of the Dicotyledons, we may, nevertheless, fairly 
— claim to have acquired sufficient data to warrant entering upon 
A the investigation of this difficult and complicated problem, a task 
which must owe a great share of its success to the aid to be ren- 
p ae a „rational ieia 
