
OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. — 255 
FAMILY XIII. Pyxinea. 
GENUS I. Pyxinz, fr. 
This genus, which NyLANpDER places between the families Uimbilicarie and 
_Lecanoree, has a Parmeliiform thallus, but lecidine apothecia. The whole plant 
frequently resembles, on the one hand, Parmelia stellaris, and on the other, 
Lecidea canescens. For the latter plant, especially, it is often mistaken: several 
specimens from Madras, Dr Wicut, in Herb. Hooker, Kew, are labelled ZL. canes- 
cens. ts spermogones externally resemble those of many Parmelice and Physcie, 
as well as some Lecidew—such as L. canescens. ‘The plant occurs in all equatorial 
countries, and in Chili. 
Species 1. PP. cocdes, Ach. 
Specimen 1.—Demerara, W. H. CampsBett (sub nom. Lecidea cocoes, Ach.) ; 
Madras, Dr WicgutT;—both in Herb. Hooker, Kew. The plant has sometimes 
greatly the aspect of Parmelia stellaris ; but the apothecia are always lecidine, 
the exciple and disk being of the same colour, which is black. The spermogones 
are generally scattered about the ends of the lacinize, as brown points, seated on 
the apices of pale, thalline papille. Sometimes they are not confined to the peri- 
phery of the thallus, but are plentifully distributed over the whole thalline sur- 
face, and among the apothecia. The body of the spermogone is always immersed 
in the medullary tissue of the thallus. The spermatia are usually linear, straight, 
or very slightly curved, with rounded or obtuse ends, about amth long, and 4) oth 
broad. The sterigmata closely resemble those of Ramalina ; they are narrowly 
linear, very delicate, branching at the base, about sth to ith long, and of equal 
thickness with the spermatia, which are given off from the apices only, as 
terminal cells or articulations. 
FAMILY XIV. LEcANOREA. 
The genera Psoroma, Pannaria, Coccocarpia, Squamaria, and Placodium are 
intermediate between Parmelia and Lecanora, as regards, particularly, their 
thallus. In some, the Parmelioid character predominates, in others the Lecano- 
rine. They cannot be properly excluded from the foliaceous class of lichens. 
GENUS I. Psoroma, Fr., p.p. Nyl. 
This genus is closely allied to Pannaria and Coccocarpia, and its spermogones 
also resemble those of these genera. The most familiar species of the genus, and the 
only British one, is P. hypnorum, Fr., which grows equally in America and Europe. 
It has short, rod-shaped spermatia, on arthrosterigmata like those of Pannaria and 
Coccocarpia. 
GENUS II. Pannaria, Del., Myl. 
The spermogones of this genus are essentially those described under Cocco- 
