particulars. The genera Ochlochete, Bulbochete, and Coleochete, 
are very closely allied to Z7tresias, Bory, (@dogonium, Link ; Vesi- 
culifera, Hassall,) and bear the same relation to it that Draparnal- 
dia, Chetophora, and Stygeoclonium do to the genus Ulothria, of 
Kiitzmg, (Spheroplea, Berk., Zyngbya, Hassall). In the former 
of these two groups of plants the sete, when present, are rigid 
continuous tubes; and the fruit, so far as has been observed, is 
not contained within an original cell of the filament, but each 
sporangium is in a new cell, formed, it is true, by the elongation 
of an original cell, but subsequently separated from it by a 
septum: this occurs in Ziresias, Bulbochete, and Coleochete. In 
Draparnaldia, on the contrary, and its immediate allies the 
diaphanous prolongations of the filaments are septate, each con- 
sisting of a series of elongated cells. The sporangia, also, in 
Draparnaldia glomerata, Ag., and Chetophora elegans, Ag., m 
which species we have observed them, are formed within the ori- 
ginal cells of the ramuli, causing the latter to assume a moniliform 
appearance. Quaternate opseospermata, which are most probably 
gemmee, likewise occur in these species, as well as in those of 
the genus Stygeoclonium of Kiitzing. 
[I am indebted to Mr. Thwaites for the above description, and 
for a beautiful figure from which our plate has been prepared.— 
Fig. 1. Fronds of OcHLOCHE/TE HYSTRIX :—vatural size. 2. The same, mag- 
nified. 3. Small portion of a frond :—very highly magnified. 
