I IO 
H. F. Wernham. 
There seems to be little room for doubt, then, that, taken as a 
whole, the Archichlamydeae are relatively primitive, while the 
Sympetalae are relatively advanced, the cohesion of the petals going 
hand in hand with general oligomery on the one hand, and progressive 
adaptation to insect visits on the other. 
With this introduction, we may proceed to trace the working of 
the evolutionary tendencies through the series Archichlamydeae, and 
attempt, by this means, to find some phyletic connection between 
this group and the Sympetalae. 
Engler has divided the Archichlamydeae into the following 
cohorts:— 
(a.) Verticillatae, Piperales, Salicales, Myricales, Balanopsi- 
dales, Leitneriales, Juglandales, Fagales, Urticales, Proteales, 
Santalales, Aristolochiales, Polygonales, Centrospermae. 
(b.) Ranales, Rhoeadales, Sarraceniales, Rosales, Geraniales, 
Sapindales, Rhamnales, Malvales, Parietales, Opuntiales, Thyme- 
laeales, Myrtiflorae, Umbelliflorae. 
The letters (a), (b), are our own ; the first group (a) coincides 
approximately with the Incomplctae of Bentham and Hooker; and 
the second (b) includes those forms which these authors have named 
Polypetalae, with the exception of the Thymelaeaies, which fall 
under the head of Incompletae in the older system. 
It will be convenient to examine first the essential organs in 
order. 
1. The Andrcecium. In group (a) the number of stamens 
shews a wide range of variability, but a distinct tendency to 
oligomery is observable within the limits of each of the cohorts 
included in Amentaceae, 1 and the Piperales. 
The transitional arrangement A=P-fP prevails in Aristolo¬ 
chiales, Polygonales, and Centrospermae—P denoting the number 
of perianth segments. 
Isomery of the androecium is a fixed character of Urticales, 
Proteales, and Santalales, and it occurs also in a good many of the 
Centrospermae and Polygonales. The stamens in these cases are 
however, usually inserted opposite the perianth segments,—and this 
is significant for our purpose as suggesting the probable abortion of 
an outer alternating whorl. 
A decided tendency to indefiniteness in numbers—here 
1 The term Amentaceae is used here to cover the cohorts Salicales, 
Myricales, Balanopsidales, Leitneriales, Juglandales, and 
Fagales, 
