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The crustaceous section of the lichen family has been examined 
by the author in a similar manner; but the description of the 
pycnides and spermogones of the lower lichens is reserved for a 
separate memoir. Neither does he profess to enter upon the ques- 
tio vexata of the physiology of reproduction in lichens generally. 
To this subject also he proposes devoting a special memoir. The 
memoir contains, inter alia , descriptions of the spermogones, or 
pycnides,, of many species, in which they either have not hitherto 
been found, or in which they are very rare and difficult of discovery. 
Such are the spermogones of Usnea barbata, Thamnolia vermicu - 
laris , Neuropogon melaxanthus , Alectoria jubata and A. Taylori, 
Evernia furfuracea , Lecanora tartar ea , &c. The letter-press of 
the memoir is accompanied by 16 quarto plates of coloured drawings 
— amounting to several hundreds — and by specimens of lichens, 
bearing spermogones or pycnides, amounting to about 140. 
Among the more interesting or important general facts brought 
out by the memoir, may be enumerated the following : — 
1. In addition to the sporiferous organs, — so long familiar to 
botanists, — called Apothecia , lichens possess more or less microscopi- 
cally minute organs, called Spermogones. The latter organs the 
author has found alike in species from arctic and antarctic, temperate 
and equatorial, regions. 
2. The spermogones of lichens may concisely be described as fol- 
lows : — In form they are usually more or less spherical or oval, ap- 
pearing on the surface of the thallus as punctiform or papillae- 
form, wart-like or barrel-shaped, bodies. In colour they are usually 
blackish, brownish, or of divers colours. In site they are usually 
scattered over particular portions of the thallus — seldom generally 
over its whole surface; they are usually more or less immersed in 
the tissues of the thallus, sometimes they are sessile on its surface, 
or on the apices of its ramifications, when it is erect and fruticulose. 
In size they are seldom sufficiently large to be visible to the naked 
eye, and are frequently so minute that they can, with difficulty, be 
recognised even with the aid of a good lens. In the latter case, 
especially, it is advisable or necessary to moisten the thallus in order 
to render them prominent from the contrast of colour or surface. 
They consist of a capsule, enclosing a cavity, that opens to the 
surface by a minute pore or ostiole, which is generally of a darker 
colour than the said capsule. From the inner wall or surface of the 
