3 
treated in the same manner as phaenogams, and it is a well known fact 
that it is the custom to unite the vascular cryptogams and the phaeno- 
gams in floristic works. So far as we are now concerned the higher 
cryptogams need not enter into the discussion, but from the nomencla- 
torial standpoint must be classed with phaenogams and there is there- 
fore left 404 species and 33 genera for all the Bryophytes and Thallo- 
phytes described in the Species Plantarum. But even in this small 
number is included the genus Spongia under Algae with 11 species of 
which at least the greater part are not even plants in any sense. Fur- 
thermore, among the Bryophytes and Thallophytes there are almost 
no extra-European species and of the European species a great pro- 
portion are Northern. In short, although as far as phaenogams are 
concerned the Species Plantarum includes characteristic representa- 
tives of different parts of the world, as far as the Bryophytes and 
Thallophytes are concerned it represents only a limited European flora. 
The question may perhaps be asked by those who have not studied 
specially any group of non- vascular cryptogams ; Although the number 
of non-vascular cryptogams in the Species Plantarum is very much 
smaller than that of Phaenogams, is it not perhaps the case that the 
ratio represents approximately the relative size of the two groups in 
nature? It has been the custom to state that the phaenogams out- 
number the cryptogams, some even saying that they are much more 
numerous. Such statements are based solely on an enumeration of 
described species and fail to give information as to the probable actual 
number of species. It is not possible to give figures on the subject 
which are up to date and the statistics of even a few years ago are of 
slight value for it is only within a few years that the study of crypto- 
gams has been pursued in other parts of the world than Europe or, to 
a less extent. North America. We can probably obtain a more 
correct opinion if we consider probabilities. The number of known 
species of Musci and Hepaticae has been very much increased in the 
last few years and although the bryological flora of Europe and North 
America is now so well known that no very large number of new species 
is to be expected there, in other parts of the world and especially in 
the tropics, it is evident that the work of exploration conducted by 
trained specialists will bring to light a very large number of new spe- 
cies. The same is true of lichens. In algae a very great increase of 
