78 MR. G. BENTHAM ON GRAMINEZ, 
Trinius, in his elaborate monograph of the tribe, divided it into 
three primary groups or subtribes— Vilfe with the callus scarcely 
prominent or quite obsolete, Agrostez with the callus globular, 
and Stipeæ with the callus obconical. In this I feel unable to 
follow him. In the first place he does not appear to have con- 
sidered what the so-called callus really is. It is not, as the name 
would suggest, an appendage to the base of the flowering glume, 
or, as he would have termed it, to the flower, but only the upper 
or prineipal part of the rhachilla or axis of the spikelet, to which 
the glume and its enclosed flower are attached, and which breaks 
off immediately above the persistent empty glumes. Its shape 
depends on the distance at which the flowering glume is attached 
above the empty ones,a distance very variable throughout the 
Order. And although the long or the short interval may be 
more prevalent or even constant in some genera, yet I have never 
found the variations so precise as to be defined by actual measure- 
ment, and the species are numerous, even in Stipa itself, where 
it is doubtful whether we should call it long or short. It is 
sometimes a useful aecessory character, but, I believe, never 
positive enough to be regarded as subtribual. It is true that no 
other simple absolute character has yet been proposed for the 
subdivision of the tribe; but we are obliged, here as elsewhere, 
to take a combination of characters, to each of which an occa- 
sional exception must be allowed. Acting on this principle, we 
might, whilst following in many respects the arrangements of 
Kunth and others, admit thirty-seven genera of Agrostes, dis- 
tributed in four fairly natural subtribes, all four of wide geogra- 
phical range, but chiefly in temperate regions, the tropical species 
mostly confined to mountain districts, and no genus, except a few 
monotypie ones, exclusively tropical. 
Our first subtribe, SrrPEx, is the long-established one of that 
name, slightly extended so as to include Oryzopsis, Muehlen- 
bergia, and their immediate allies, the close connexion of which 
with Stipa has been frequently suggested. The subtribe thus 
formed would be characterized by the paniculate inflorescence 
not condensed into the cylindrical spike of Phleoidex, by the 
rhachilla of the spikelet not produced beyond the flower except 
in the single species of Brachyelytrum, by the awn of the flowering 
glume terminal, not dorsal as in Euagrostesz, and especially by 
the grain being very closely enveloped in the fruiting glume. 
In the majority of species these characters are well marked; but 
