178 The American Naturalist. [February, 
the number of fungi will increase considerably. In fact the Venetian 
Hymenomycetes were until now scarcely studied and the interior prov- 
inces like those of Venezia, Rovigo, Vicenza, Belluno, Udine, which 
comprise the Alpine region which will give us without doubt a large 
contribution of new forms, are in a mycological respect almost entirely 
unexplored. I am therefore convinced that when all the Venetian 
territory is well explored, we will have at least 7,000 fungi in its Flora, 
a number which compared to that of the Phanerogams (2,939) sur- 
passes it by certainly ł}. According to this proportion if we have to- 
day more than 105,000 Phanerogams in all the world, the fungi in 
order to exceed them by ł ought to ascend to about 245,000. This 
calculation cannot be accused of exaggeration when we see that the 
greatest part of the fungi being parasites, a connection between them 
and the hosts (for the most part Phanerogams) must necessarily exist. 
But this is not all. We have rich and accurate repertoria of fungi 
according to their hosts; as the general one of Westendorp, the one 
for Venice of Cuboni and Mancini; the very recent one for North 
America of Farlow and Seymour. A glance at these repertoria shows 
us at once that there are very many Phanerogams which harbor para- 
sitic fungi by tens and hundreds many of which are exclusive to them. 
We have moreover careful monographs of the fungi which grow upon 
the vine (Pirotta, Thuemen), on the Lemon and Orange (Penzig), on 
the Mulberry (Berlese). Now the fungi which grow upon the vine are 
according to the last census of Thuemen (1892) in number 599, those 
on the lemon and orange 190, those on the mulberry 200. When we 
consider these hosts as generic groups (Vitis, Citrus, Morus) and caleu- 
late that for each of these groups alone, on an average, 40 per cent. of 
the parasitic fungi are exclusive to them (and not wandering oF pam: 
genous) we have: for the genus 
Vitis, proper species of fungi 288 
Citrus 76 
Morus 80 
the average of which numbers is 131. Now the genera of greater pl af 
of Phanerogams being, according to Bentham and Hooker 8,41 ; 
we reckon 131 fungi proper for each one of these genera, there a ded 
the huge cypher of 1,102,627 parasitic fungi, to which must be l 
that of terrestrial and non-parasitic (about 11,000) in all 1,1139% 
Certainly this number does not appear at all impossible when We ae 
that the data are taken from genera (Vitis, Citrus, Morus) which a 
tains few species in comparison with others (e. g. Solanum, 4® h with- 
Euphorbia) which possess several hundred more of them, whic 
