458 MR. H. B. GUPPY : PLANT-DISTRIBUTION 
the great families and the age that witnessed their subsequent differentiation 
are things apart, and cannot be dealt with by the same method. 
If one were asked how such a view of distribution could be reconciled with 
that of the animal world, one might reply that since plants and animals 
have been developed on quite different plans, the plant requires an applica- 
tion of the Darwinian theory of evolution, in which this distinction is 
recognized. In the one case development has centred around provisions 
for securing the continuance of the like. In the other it has been concen- 
trated on the production of a higher order of beings culminating in Man. 
The first secured, the second became possible. 
Note on the sub-divisions of the Dicotyledons. 
In order to make a further statistical comparison of the Dicotyledons 
with the Monocotyledons, the number of families in the first being 
according to Engler's system more than five times those of the second, 
the Archichlamydez have been broken up into four groups, making with 
the Sympetale five groups for the class. For this purpose the system of 
Engler was preferred, since a scale of development is implied in the 
arrangement adopted ; whilst with that of Bentham and Hooker the placing 
of more than a fifth of the families there recognized in the Incomplete 
makes a linear classification impracticable. Yet it was the Incomplete that 
led the writer to pay attention to this matter, with the result that the group 
viewed from this standpoint appears to be very far from an anomalous 
group. On the contrary, when treated statistically it proves to be the most 
typical, as far as percentages are concerned, of all the groups of the 
Dicotyledons. 
Assuming that the series—Monocotyledons, Archichlamydes, Sympetale 
—represents a scale of plant-development and that the same is indicated in 
the arrangement of the groups of families of the Archichlamyde:e, the writer 
broke up the last-named into four groups and obtained the following 
succession :— 
Monocotyledons, holding 43 families. 
( Group A. Cohorts 1-14 with 37 families. 
Ec p TOR. 2 4d a 
Aychichlamy deze J Sid s dba os 
Dicotyledons E. D sc X42 8 
Sympetale, holding 51 families. 
Group A includes 25 of the 37 families in Monochlamyde: or Incompletze 
of Bentham and Hooker. Group B comprises the cohorts Ranales, 
Rheeadales, Sarraceniales, and Rosales; Group C, the cohorts Geraniales, 
Sapindales, and Rhamnales ; and Group D, the cohorts Malvales, Parietales, 
Opuntiales, Myrtiflorze, and Umbelliflore. 
Together here we have six groups which we will term the Primaries, and 
