PYCNIDES OF CRUSTACEOUS LICHENS. | 237 
stylosporoid spermatia of abietina, which are sometimes 45153 to 5555. Those of pulvi- 
nata, of the subvermiform type, are soyo to 5355. Then follow the acicular or linear 
forms of fusco-atra, contigua, albo-atra, DNA Nh and canescens, 395g to royo; of dis- 
pero cts vernalis, decipiens, 1000 to 3550: Of uliginosa, pachycarpa, cupularis, 
sooo tO sogo; Of pineti, luteola, cgi 5060 tO 15500; and of chalybeia, Ehrhartiana, 
rivulosa, lurida, and sublurida, 4354355 to 43499. A very common size is between 
3000 and 4555 long. Their breadth is much less variable than their length, ranging 
from 45455 to 55-400. Their size, when attached, is sometimes double that which they 
possess when free; whence it would appear that they sometimes divide into two, and, 
exceptionally, into more than two, segments. 
(A) Sterigmata are most frequently linear, simple and short, as in luteola; frequently 
. branching from the base in a subdigitate manner, as in 4Alectoria, Cladonia, Ramalina, 
Roccella, Squamaria, Lichina, and Ephebe*, or composed of a few narrow, longish, and 
frequently somewhat irregular articulations, jointed to each other at various angles, as 
in morio, contigua, decolorans, canescens, albo-atra, sanguinaria. Sometimes they appear 
to become very much thickened from deposits on the interior walls of the constituent 
cellules. Nylander (Prod. p. 101) says that, as a general rule, the genus Lecidea has no 
arthrosterigmata: but he probably restricts that term to sterigmata of the character of 
those of Sticta, Collema, Physcia, Placodium, and Umbilicaria, which consist of numerous 
short subspherical or subcubical cellules. As in the case of the spermatia, their length 
is much more variable vp their breadth. The AME in — is ggoo; While the 
length varies from 535 50 to 1355s in the raa nR ; 1000 tO 1355 In fusco-atra, de 
— ; 1000 t0 1359 in isle 1 500 to 49s in moe o and MI 5060 to 
5000 In rivulosa and premnea; 155 to zogo in glaucolepidea; 5555 to 5555 1 ata. 
EL Pycnides not unfrequently occur in the genus Lecidea, either in addition to sper- 
mogones, or (apparently) substitutionally for them, and associated with, or without, apo- 
thecia. Their number is not, however, so great, nor is their variety sufficient, to render 
it necessary to attempt a general description similar to that given of the spermogones. 
They occur in. parasema, albo-atra, luteola, Ehrhartiana, cladoniaria, vernalis var. Wall- 
rothii, and Abrothallus Smithii. They resemble spermogones in position, size, and other 
external characters. Usually they are black, and punctiform or papillæform, with a 
‘simple cavity. The basidia are usually short,—always simple and linear. "The stylo- 
spores, however, vary considerably in character. "They are variously linear-oblong, ellip- 
soid, oval or obovate, pyriform, subspherical or irregular, generally simple, sometimes 
1-septate, or containing M or granular matter, their length varying from 1355 
to 3050, their breadth from 325 to 5555: 
Not only are Spermogones and Pycnides apt to be confounded with each other, till their 
internal structure is revealed by the microscope; but both are liable to be mistaken for 
various Microparasites, of the nature either of :— 
(a) Fungi: e.g. various Spherie ; Torula lichenicola ; 
as on Hookeri, rupestris, contigua, parasema, lurida, canescens. 
* As figured in my first Mem. Spermog. plates iv., V., Vi., vii., viii, and xv. 
VOL. XXVIII. 
