38 Mr. Woops on the Genera of European Grasses. 
are only 2, not much alike in general appearance, 4. globosa and A. agro- 
stidea, and of these he calls the first * species anomala," and doubts if it do 
not rather belong to Aira: yet this is, I believe, the original species. In 
A. globosa the outer palea is rather firmer than the glume; in A. agrostidea 
the palez are the thinnest and most pellucid. 4. agrostidea has perfectly 
smooth pales, contrary to the generic character of Airopsis. In most of the 
` Aire the seed seems to be loose and the corolla unchanged; but in A. caryo- 
phyllea, precoz, capillaris, pulchella, and probably some others, the paleæ 
harden upon the seed. These are very different in habit from 4. flexuosa, 
and I have doubted whether it might not serve as a foundation for remodelling 
the genera, but I have not materials for following out the investigation. "The 
outer palea is without any prominent nerve or rib in the hitherto acknow- 
ledged species; but I have a small Grass from the neighbourhood of Rome, 
which in many respects is an Aira, and with the habit of Aira caryophyllea, 
where the outer palea is strongly ribbed, much firmer than the 
glume, and fully 
as long, 
but it does not harden on the seed. I propose to call it Aira costata ; 
paled inferiore costatd glumis firmiore immutatd. 
The single flowers of Lacurus separate it from the rest of the tribe, 
compact head might lead the student to 
examination of the florets will certain] 
Of Triserum Kunth says, 
T. phleoides, T. molle, T. toluccense, 
anum, T. Cavanillesii ave described i two. flowers 
Why do they not belong to Aira? * | 
on the comparative length of the lumes ich i : : 
siderably exceed the spicula. x this is MEN eee 
: ET not the case in 4. Jlexuosa, which 
perhaps might be joined to Trisetum, In habit the difference is more marked 
and the 
place it among the Phleineæ, but an 
dense in Trisetum than in most of the 4i = E: 
dira precor, which nobody thinks of uniting wi Perhaps, not more than in 
