(18) 
tyloidee bi- rarius quadriloculares incolores. Spermatia oblonga ; 
sterigmatibus pauci-articulatis. Thallus tereti-compressus, dichoto- 
mo-ramosissimus, implexus, appressus, cartilagineo-coriaceus, fibrillis 
obsoletis. 
An ambiguous lichen from rocks in western Texas, where it was dis- 
covered by Mr. Wright. The appressed-orbicular habit, comparable with 
that often exhibited by Parmelia lanata, but more regular, associates it 
with the Parmeliei; and it possesses, in fact, some general, but super- 
ficial resemblance to narrow-lobed states of Physcia aquila, v. detonsa. 
Taking Physcia, as arranged by Nylander, to include the variously con- 
trasted groups distinguished here as Theloschistes and Physcia, the plant 
before us may not appear ill-placed between these groups, though their 
real point of transition may be rather to be sought in P. intricata (Desf.) 
Scher. The almost terete, or at length compressed-terete, somewhat 
two-edged thallus of the Texas lichen is neither, however, foliaceous, nor 
much better comparable with the constricted types of Physcia (P. intri- 
cata; P. ciliaris, v. angustata) from association with which moreover the 
structurally distinct spores (as we must here regard them) at once sepa- 
rate it; as they do also, the want of any other features of resemblance 
being taken‘into consideration, from Theloschistes. As it is here placed, 
a certain analogy with Roccella is suggested ; and, at the tips of the thal- 
lus at least the plant, though much more delicate, is really comparable in 
habit with some slender, much-branched forms of R. phycopsis; while 
the spores, though rarely exceeding the bilocular stage, occur in a more 
developed one, also suggesting Roccella: with which genus it yet sharply 
contrasts in the anatomical features of the thallus. Spores 0.009-0.014 
millim., long, by 0.0035-0.0055 millim., wide. 
IX.—THELOSCHISTES, Norm., emend. 
Tuckerm. Lich. Calif. p. 8. Theloschistes sectt. A, B, Norm. Con. p. 16. 
Borrerz, Corniculariz, Dufouree, Parmelie, et Lecanore spp., Ach. 
L. U.; Syn. Evernie spp., et Parmelia sect. D (Xanthoria) Fr. 8. 0. 
V. pp. 236, 243. Evernize spp., et Parmelie sect. 1, spp., Fr. L. E. 
pp. 27, 72. Cornicularie sp., Physcie spp., et Parmelie sp., Scher. 
Enum. Blasteniospora. Trev., cit. Mass. Tornabenia, Physcie spp., 
et Candelarie sp., Mass. Mem. pp. 41,146. Koerb. Parerg., pp. 20, 
37, 62. Physcia sectt. A, a, B,b, Nyl. Prodr. Gall. p. 59; Syn. 1, 
p. 406, t. 8, f. 49, 51-2. Physcia sect. 1, Tuckerm. Obs. Lich. 1. c. 4, 
p. 3384. Theloschistes et Xanthoria sect. A, Th. Fr. (Lich. Arct. p. 66) 
Gen. pp. 51,60. Physcia, Mudd Man. Brit. Lich. p. 111. Nanthoria, 
Stizenb. Beitr. 1. c. p. 173.——Structuram exposuerunt Tulasne, Mém. 
pp. 16, 43, 60, 144, t. 1, f 1-7; Schwendener, Untersuch. 1. c. 2, pp. 
158, 162, t. 5, f. 16, 17 et 3, pp. 154, 160, t. 8, f. 10-13. 
