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groups of plants, the bacteria and the moulds (Mucorini), that can- 
not be disregarded. While their structure and function causes 
them to stand somewhat midway between plant and animal, it 
would seem more consistent in a systematic arrangement to place 
them at the bottom of. the plant world. 
2. Until the inter-relations of the algae and fungi can be more 
definitely known and some suitable system devised that shall make 
it possible to unite allied forms on a rational basis, it will be best 
to maintain this unnatural and heterogenous group which we call 
Thallophyta. It is true, as has been stated, that the group is 
Practically undefinable, but that is always true of the last division 
of any series in which those forms are placed that do not conform 
to any known natural arrangement. The close alliance of some 
of the lower fungi and algae .absolutely precludes the idea of 
establishing these as primary groups, and of the various systems 
of subdivision that have been maintained there are none thet seem 
to be founded on real or natural relationships. Unsatisfactory as 
the group is, we see no present improvement that can replace it.. 
3. As has been often maintained, there is not a wide distinction 
between a simple Riccia and some of the green algae, and the 
group Archegoniata is not entirely distinct at its lower limit. 
This, however, is true of any great group when its outliers are all 
known, for evolution has not yet resulted in the destruction of all 
the connecting links. We have for the same reason excluded the 
Characeae from this group because of their apparently stronger 
affinities with the other green algae. For a similar reason we 
have included the Gymnosperms at the upper limit because their 
affinities when properly. understood seem to link them more 
strongly here than with the higher plants. 
With these limitations we present the following outline of the 
classification of the Archegoniata. 
Sub-kingdom ARCHEGONIATA. 
Class BRYOPHYTA. 
(Sub-class Hepaticae.) * 
Order Marchantiales. 
*I have placed these subgroups in parenthesis as representing group names that 
Modern research seems destined to retire toa merited oblivion. I have elsewhere 
discussed their abandonment more in detail. Cf Proc. A. A. A.S. 43: 259-274, 1894. 
