58 MR. G. BENTHAM ON GRAMINES. 
by their inflorescence; the spikelets are singly scattered or 
clustered along the inarticulate branches of the panicle or, in the 
very few cases where they are in pairs, the two of each pair are 
perfectly similar. Tristeginez are distinguished from Agrostex 
by the characters which separate the two primary series Panicace& 
and Poacem. The tribual name was given by Nees from the genus 
Melinis, which he published as Tristegis, believing it to be new ; 
and although its identity with Beauvois’s Melinis has since been 
established, it does not seem worth while now to alter the tribual 
name, which has been pretty generally adopted. Of the thirteen 
following genera, several of them common to the New and the 
Old World, the first four, with three glumes to each spikelet, are 
temperate or subtropical, the following nine all tropical, with four 
glumes to the spikelet. 
1. TAURBERIA is anew name I have been compelled to substitute 
for Greenia of Nuttall or Sclerachne of Torrey, both of which had 
been preoccupied. The genus is limited to two North-American 
species which Steudel has proposed to unite with Zimnas; but 
they differ essentially from it in the awn of the flowering glume 
terminal, not dorsal, in the distinct styles, and other characters 
besides habit. I have named the genus after G. Thurber, who has 
much studied North-American Graminere and worked them up 
for S. Watson’s Californian Flora. The genus formerly dedi- 
cated to him by Asa Gray has since proved not to be distinct from 
Gossypium, to which it has been reunited by the author himself. 
2. LTMNAS is a single perfectly distinct species from East- 
Russian Asia, well described and figured by Trinius. 
3. Porvrocos, Desf., a genus readily known by its dense in- 
florescence and the long awns of its empty glumes, is one of those 
which interferes in some measure with general classification. It 
has usually been placed in Agrostes; but the very decided arti- 
culation of the pedicel removes it from that tribe to the Triste- 
gines, where in many respects it is allied to Garnotia. It consists 
of about ten species, dispersed over the temperate regions both of 
the northern and the southern hemisphere, one of them almost 
cosmopolitan, but they are rare within the tropics. It was first 
published by Savi under the name of Santia in the Memoirs of the 
Italian Society of Science, a publication which had so little circula- 
tion that the name has not found its way into standard works, and 
that of Desfontaines has now been so long and so generally in use 
in all countries, that it would only create useless confusion now to 
