BRIEFER ARTICLES 
PYRENOTHRIX NIGRA, GEN. ET SP. NOV. 
’ (WITH FOUR FIGURES) 
The material upon which the new genus and species of lichens here 
described is based was collected by Professor RoLAND THAXTER, of 
Harvard University, in Florida in 1897. I wish to acknowledge my 
indebtedness to Professor THAxTER for his kindness in placing the 
material at my disposal for study and description. On account of the 
distinctive combination of a byssine thallus and a teases ode fruit 
this new genus may appropriately be named as follows 
Pyrenothrix, gen. nov.—Thallus crustaceo-byssinus ecorticatus sub- 
strato arcte adnatus gelatinosus, ex hyphis tenuibus leptodermaticis 
crebre septatis ramosis, filamenta gonidiorum dense obducentibus. 
Gonidia ad species Scytonemae pertinentia filamentis implexis. Peri- 
thecia tenues coriacea pseudoparenchymatica, integra simplices recta 
nuda nigrescentia, in gonidiis sessilia nunquam immersa, ostiolis parum 
distinctis. Paraphyses persistentes simplices filiformes. Asci clavati. 
Sporae ee murali-divisae cellulis subcubicis. Sper- 
magonia non visa. 
This new genus, by reason of having gonidia of the Scytonema type and 
fruit of the perithecial form (figs. 1, 2), would appear to belong most naturally 
to the family Pyrenidiaceae, as coumtituted by ZAHLBRUCKNER (ENGLER and 
PRANTL, Die Natiirlichen Pflanzenfamilien, Teil I, Abt. 1, p. 76), but differs 
from all of the genera of that family hitherto described in the byssine character 
of the thallus (fig. 1), and in the muriform spores (fig. 4). When examined 
under the microscope, the structure of the thallus and the relation of hyphae 
— ~ebacgag oy sonia ig nee vegisiee that of Coenogonium (fig. 2). Without 
question, ““What isa lichen ?”’ it may be said that 
if Racca | is a lichen ety P imei is a lichen, as the two are strictly 
analogous. That the perithecia are not those of a secondary parasite or merely 
accidentally associated with the filaments of the alga is proved by the observa- 
tion of early stages in their development showing their origin from the web of 
hyphae that envelop the gonidia (fig. 3). 
Pyrenothrix nigra, sp. nov.—Thallus fusco-nigricans byssinus sub- 
strato arcte adnatus late effusus non limitatus, sicco nec flaccido nec 
513] [Botanical Gazette, vol. 64 
