112 DR LAUDER LINDSAY ON THE SPERMOGONES AND PYCNIDES 
c. Parasitic fungi,—especially of the genus Spheria. 
d. Minute Verrucarias. 
é. Parasitic Lecidew—as L. vermicularia, L. alectorie, L. cladoniaria, and 
L. obscuroides. 
From all these bodies they are only to be distinguished by microscopical 
examination. 
II. Position of the spermogones on the thallus, and in relation to the apothecia. 
They occur generally on specimens bearing also apothecia; sometimes, how- 
ever, only on sterile specimens of species whose apothecia are common; and still 
more rarely on species or specimens never yet found bearing apothecia, as in 
Thamnolia vermicularis and Dufourea madreporiformis. 
1. Superficial —oOn the foliaceous, horizontal thallus, usually scattered about 
the margins of the lobes or lacinize, as in many Parmelias and Physcias. In this 
case they are situated external to the region occupied by the apothecia. 
In exceptional cases they are scattered generally over the whole surface, and 
are then intermixed with the apothecia, as in Parmelia conspersa, P. encausta, 
and P. stygia. The same occurs sometimes in species with a fruticulose thallus, 
as in some Cladonias and Roccellas. 
They are sometimes confined to the plicee of the thallus, as in some species of 
Sticta and Ricasolia. 
In some Placodia, which approach the true crustaceous type of thallus, sper- 
mogones are scattered,—isolated, or in groups of two or three,—on the thalline 
areolze, central or peripheral, generally the latter, sometimes both. 
2. Marginal__In some species with a foliaceous thallus, they are seated 
directly on the margins of the lobes, to which they give a denticulate character, 
as in many Platysmas, in Collema and Leptogium, in Parmelia perforata var. den- 
ticulata, Nephromium tomentosum, and some forms of Ricasolia herbacea. They 
are also marginal in some species, with a subfoliaceous or fruticulose thallus,—as 
Parmelia Fahlunensis, P. tristis, and Evernia Richardsont. In other lichens, they 
are seated at the ends of cilia or processes given off from the margin of the 
thallus, as in Cetraria islandica, and some forms of Nephromiwm tomentosum. 
3. Terminal.—In several species or genera, having a fruticulose or filamentous 
thallus, the spermogones are scattered toward the ends of the thalline segments or 
ramules, as in Usnea, Ramalina, Ephebe, and Roccella. In Cladonia, they gene- 
rally either form the tips of the tapering, simple, or branching podetia, as in C. 
rangiferina, C. furcata, and C. uncialis; or they fringe, as tooth-like processes, 
the margins of the scyphi, asin C. pyzidata. In some cases they are seated on the 
same podetia with the apothecia, as in most species with scyphi; in others, they 
are on different podetia, as in those with a ramose thallus, such as C. rangiferina, 
In both cases, however, they are in close proximity to the apothecia. Some Cla- 
donias have spermogones on the surface, as well as the margins of the scyphi. 
