OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 271 
margins of the lobes,—they are usually tubercles or warts, resembling frequently 
knobs or buttons. In the latter case, they give the margins of the thallus a den- 
ticulate or warted character. Sometimes, though rarely, they are found both on 
the sub-erect margins and on the flat surface of the thallus near the margin, as 
in some forms of C. melenum. From their pale-yellowish or buff colour, and 
discoid form, they frequently resemble seeds imbedded in the thallus. Sometimes 
they are of a greenish tint, having acquired some of the colouring matter of the 
thallus. The size of the spermogones is pretty uniform; in C. plicatile, the 
breadth is xth to jth. The envelope is of a brownish or yellowish cellular 
tissue. The ostiole is generally brown, minute, and round,—central,—of a deeper 
colour than the rest of the organ. Sometimes it becomes, in the old state, patent 
and conspicuous. The spermogone is not easily enucleated, from its adhesion to 
the surrounding tissue of the thallus, especially when the latter is moistened and 
gelatinous. It is generally necessary, for the examination of the spermogones of 
Collema under the microscope, with a pair of very fine-pointed scissors to cut away 
a portion of the margin of the lobe, with one or more spermogones included, making 
the incision, if possible, through a spermogone. On subjecting such a section to 
pressure between glass slides, in a drop of water under the microscope, the emission 
of myriads of spermatia may be easily seen. These spermatia are in all cases 
short, rod-shaped, and with obtuse ends; they vary in length from gsth to anth, 
—the majority being about goth to smth long, with a breadth of igth to x hqth. 
The sterigmata, in all specimens examined by me, are articulated,—sometimes 
ramose,—about th to qth long, composed of short, roundish, or cubical cells, 
with thinnish walls compared with the component articulations of the arthro- 
sterigmata of Stzcta. 
SPECIES 1. C. auriculatum, Hoffm. 
Specimen 1.—Scurer exs. 432 (sub Parmelia granosa a. vulgaris ; on 
stones among moss, Switzerland. There are two specimens, neither of them 
bearing apothecia; on the right-hand specimen in my copy (original ed., 1842), 
Spermogones occur. In external form, situation, and structure, they closely re- 
semble those of Leptogium saturninum. 
SPECIES 2. C. flaccidum, Ach., 
A widely-spread and familiar species, occurring in Europe, Asia, Northern 
America, and New Zealand. The fact of a variety pyrenodes being mentioned 
by FLorow shows that the spermogones of this species have not escaped the 
attention of the older lichenologists. He evidently alludes to the spermogones 
as his “ Pseudo-peritheciis minutissimis, fusco-atris, vertice poro vertusis.” 
Specimen 1.—On Aghalie Bridge, Lagan Canal, Ireland; D. Moore 3; in Herb. 
Carroll; with apothecia. The Spermogones are small, brownish-yellow disks, 
immersed in the substance of the thallus, and scattered about the margins of its 
