268 Alfred Gundersen. 
An Inventory of Families. 
If the desirability of uniform families should be approved by 
a number of botanists, or if possible by botanical institutions and 
societies in different countries, something like an inventory of 
facts and of conflicting opinions which appear to have a bearing 
on family sequence might be practicable. Such an undertaking 
would probably clarify many points, whether or not it should 
result in any world agreement. This would by no means 
require a re-writing of the Pflunzenfamilien. Details of 
genera and species, except in the cases where these affect the 
position of a family, would only confuse the issue. Evolutionary 
sequence is associated with more or less uncertain interpretation of 
characters ; these characters are in nearly all cases very different 
from those by which plants are identified. Thus limited a survey 
might be completed within reasonable time. A single volume 
with a preliminary sequence, indicating the various possible 
arrangements, might contain more information than great works 
which include miscellaneous subjects. 
The sequence adopted for the diagram on the opposite page 
is intended to call attention to some of the specific questions 
involved. The geologic distribution must be considered as only 
approximate. There are four main changes from the PHanzenfamilien 
1° L ycopodiacece etc. are not interposed between the ferns and seed 
plants; 2° ferns begin with eusporangiate forms as shown by Bower ; 
3° the ancient and diversified group of gymnosperms requires a 
greater number of families, as used by many authors ; 4° angiosperms 
begin with dicotyledons. 
The 
families might 
then begi 
somewhat as follows: 
Lycopodiacese 
Lycop 
1 
Sagenopteris 
Lepidodendrales 
Marsiliaceae 
Mars 16 
Selaginellaceae 
Selag 
2 
Salviniaceae 
Salv 17 
Isoetaceas 
Isoet 
3 
Psilotaceae 
Psil 
4? 
Ptevidospevmce 
Cycadaceae 
Cycad 18 
Sphenophyllales 
Zamiaceae 
Zami 19 
Pseudoborniales 
Calamariales 
Bennettitales 
Equisetaceae 
Equis 
Cordaitales 
Ginkgoaceae 
Ginkg 20 
Coenopterideee 
Psaroniece. 
Taxaceae 
Taxac 21 
