(201 ) 
L.—XYLOGRAPHA, Fr., Nyl. 
Fr. Syst. Myc. 2, p. 197. Nyl. Classif. 2, p. 187; Enum. Gén.1.c. p. 128; 
Prodr. p. 147; Lich. Scand. p. 249. Mass. Miscell. Lich. Coemans 
Not. sur quelques Crypt. p.14. Th. Fr. Gen. p. 99. Koerb. Parerg. 
p. 275. Stizenb. Beitr. 1. c. p. 153. Lichenis, dein Opegraphe sp., 
Ach. Prodr.; L. U. p. 253. Hysterii sp., Wahl. Pers. Limborie sp., 
Ach. Opegraphe sp., Fr. & Tuck. in Lich. Amer. exs. n. 97. 
Apothecia ex angulato-patelleeformi seepius lirelleeformia, excipulo 
proprio ceraceo. Spore ellipsoidez, simplices, decolores. Sper- 
matia acicularia; sterigmatibus simplicibus. Thallus crustaceus, 
uniformis ; aut obsoletus. 
Opegrapha parallela, Ach., was referred by Fries (1. c.) to Fungi as a 
distinct type (Xylographa) closely allied to the genus Stictis ; and the same 
botanist, at one time, distinguished from Lichens, ‘cruste defectu et loco 
natali,’ Calicium turbinatum, Pers. (Sphinctrina, Fr. 8.0. V.). Inrestor- 
ing afterwards the latter to Lichens (Z. #.) Fries restored it also to 
Calicium ; and it is difficult to see how he could have done anything else, 
or how we can call the now general distinction of Sphinctrina (as a 
lichen-group) from Caliciwm, other than arbitrary. The case of Xylo- 
grapha is without doubt less clear. The North American X. opegraphella 
is obviously a lichen; akin too, generally, we can scarcely deny, to 
Opegrapha and Graphis; and congenerical with the less distinctly 
lichenose European species; in which case analogy requires that the 
apothecia of all the forms should be taken for equivalent to the same 
organs in the Opegraphei proper. But there remains still, to separate 
this little group, at least from Opegrapha, the softer texture of the biato- 
rine exciple, and the unilocular spores.‘ In view of analogies in other 
tribes, we cannot lay great stress on the latter of these differences, either 
here, or in Lithographa, Nyl.; but the former is less open to question, and 
looks evidently away from Opegrapha, and in the direction rather of 
Graphis. Itis this last genus which furnishes us with all the most remark- 
able exhibitions of what may be called biatorine exciples to be found in 
Opegraphei ; and this affords, in its, in one sense, extremest section 
(Fissurina) conditions of the exciple perhaps not wholly without reason 
to be compared with states of the fruit of Xylographa opegraphella. 
1 Perhaps not always unilocular. The ‘goutelletes claires, souvent au nombre 
de deux, placées a chaque extrémité de la spore’ (Coemans, |. ¢.) are characteristical 
in other forms as well asin X. parallela, and suggest now a bilocular spo: + not 
unlike those of several Biutorw, as comparable also with decolorate Pyrenula- 
types. And Dr. Nylander has just described a Xylographa (X. platytropa, Nyl. 
in Flora, 1868, p. 163) with ‘colourless or pale brown spores, which are 6-10-locular, 
and the cells oftener bilocular.’ In view of this, the spores of the other species 
should be taken for decolorate rather than typically colourless. 
26 
