PYCNIDES OF CRUSTACEOUS LICHENS. 281 
taining them bear a more intimate topographical relation to the Arthonia than to the 
Opegrapha. The basal cellular tissue is brown; and many of the sterigmata have the 
same colour, derived, no doubt, from their said matrix. 
In the second form of spermogone the conceptacles are small, black or brown, puncti- 
form, and more abundant, having rod-shaped spermatia sopo X 15500, on very short, 
simple linear sterigmata. Basal cellular tissue here also brown. 
Pycnides also occur—of the character of Pyrenothea vermicellifera rather than of P. 
leucocephala—though somewhat resembling externally forms of both. They are large, 
distinct, roundish, white-pruinose tubercles, containing stylospores like those typieal of 
P. leucocephala. Were any apothecia of Lecidea abietina present they would be referred 
to it; and even in their absence some lichenologists would probably so refer them. 
Species 3. A. IMPOLITA, Borr. (Mudd, Br. Lich. p. 248). 
According to Körber (Syst. Lich. Germ. p. 277), its spermogones are, in part at least, 
Pyrenothea insculpta, Wallr. (which P. stictica, Fr. pr. p., P. gregaria, Flot., Verru- 
caria byssacea, Ach., and Thrombium byssaceum, Weig.). He describes them as occurring 
in Germany on very old oaks, in the fissures of the rugged bark, and says the spermatia 
are rod-shaped (or linear). 
Specimen 1. On the bark of old oaks, Switzerland: Hepp Exs. No. 229, sub Throm- 
bium byssaceum, Weig. No apothecia are present. The spermogones are abundant, 
seattered over the whitish subpulverulent thallus, as largish, distinet, black tubercles, 
very irregular in form and size, with a white-pulverulent margin. The envelope is of 
deep-brown cellular tissue. "The spermatia are in myriads, short, oblong, or rod-shaped, 
on very short, simple, linear sterigmata. Hepp figures the spermatia as ellipsoid. 
Specimen 2. On oaks, Switzerland: Scher. Exs. No. 286, sub Verrucaria insculpta. 
Spermogones are very minute, black, punctiform, copiously distributed among the dege- 
nerate apothecia. Spermatia are rod-shaped, +555 X 55-000: on linear, simple sterig- 
mata, 1355 long. 
Specimen 3. Nylander's Exs. No. 83. Spermatia ellipsoid, 3555 X 50570. 0n simple 
sterigmata about 3757 long. 
Specimen 4. Batchcott, Hay Wood, Herefordshire: Leight. Exs. No. 131. Spermo- 
gones are interspersed among the apothecia in the left-hand specimen in my copy, as 
numerous, small, brown, translucent, punctiform bodies, containing spermatia that are 
linear (or cylindrical), but mostly curved, even while attached. The sterigmata are 
simple, or branch digitately; but their outline is most irregular, very wavy or tortuous. 
Both spermatia and sterigmata differ so much from those in the spermogones of the type, 
that it is difficult to regard them as belonging to the Arthonia. By their characters, 
the spermogones in Leighton's No. 131 might belong to Lecanora subfusca ; but no traces 
of its apothecia occur*, 
* Vide also description and figures of spermogones and pycnides of this species in my paper on Arth. melaspermella, 
p. 273, plate vi. figs. 7 & 8. 
