bá ON GENERA AND SPECIES. 
of growth and venation, but with the exception of five E 
species of Platycerium he retains the whole under the | 
genus Acrostichum. ; 
Of the tribe Aspleniew he describes over 300 species, all 
comprehended under the genus Asplenium, except two — 
species which constitute the two genera Allantodia and ` 
Actinopleris, With regard to Scolopendrium, some authors - 
consider it as a genus scarcely separable from Asplenium, — 
but in the “Species Filicum” it is characterised as a dis- ` 
tinct tribe under the name of Scolopendriew. It consists of ` 
nine species, which agree in general habit with Asplenium, | 
and present no special character to justify their separation 
as a tribe from Asplenies. E 
We give another instance,—in speaking of Hypoderris, — 
he says :—“ Considering as I do that the primary divisions - 
should be taken as much as possible. from the fructifi- ` 
cation, I have no hesitation in placing Hypoderris among 
the Dicksonie and near to Woodsia.” No three genera ` 
can be more distinct in natural affinity than these—that ` 
is, as regards habit and anatomical structure; the only 
similitude is between Hypoderris and Woodsia, which have 
discal punctiform sori, with a very membranous cup 
indusium, therefore in that character are more properly 
though artificially related to Cyathea than to Dicksonia, 
which has marginal sori with cystiform indusia opel a 
outwards. 
Again, take the case of Matonia, a rare Fern with fan» 
shaped fronds, in every respect allied to Gleichenia in 
habit, and also in the ring of the sporangia being hori- 
zontal, and differing only from Gleichenia in the sori being 
furnished with an inverted cup-shaped indusium, attached 
by its centre as in trae Aspidium and Polystichum. 
Although such is the case, Sir William Hooker follow 
