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lata. U. scruposa is common throughout the country, on granitic rocks 
and on the earth, from New England to New Mexico (Mr. Fendler) recurs 
in its calcareous conditions in Nebraska (Dr. Hayden) and is especially 
fine, in terricoline states, in California (Mr. Bolander). The curious form 
of the same species in which its apothecia occupy parasitically the thallus 
of Cladonie (v. parasitica, Sommerf. Lapp. p. 100. Nyl. Scand. p. 177) 
is also found here (Rhode Island, Mr. J. L. Bennett) and particularly fine 
specimens have been sent from California (Mr. Bolander).——U. actin- 
ostoma, Pers., is as yet very rare; having only occurred at Weathersfield, 
Connecticut (Mr. Wright) at Aiken, South Carolina (Mr. Ravenel) and 
(on lime-rocks) in Kansas (Mr. E. Hall). 
XXXV.—THELOTREMA, (Ach.) Eschw. 
Eschw. Syst. p. 15, et Lich. Brasil. 1. c. p. 172. Fr. S. 0. V. p. 269, et L. 
E. p. 427. Nyl. Enum. Gén. 1. c. p. 117; Lich. exot. 1. c.; Prodr. Fl. 
N. Gran. p. 40; Syn. Lich. N. Caled. p. 32; et Ascidium, Ejusd., ll. 
cc. Tuckerm. Obs. Lich, 1. ¢. 5, p. 405; 6, p. 269; Lich. Hawai. 1. c. 
p. 227. Volvaria (Gyrostomo excl.) et Thelotrema, Stizenb. Beitr. 1. c. 
p. 168. Thelotrema pr. p., Ascidium, et Myriotrema, Fée Ess. pp. 
41,49; Suppl. p. 88. Thelotrema, Ascidium, et Leptotrema, Mont. 
Pl. Cell. Cub. p. 163, t. 8, f. 2; Crypt. Guy. p. 55, t. 16, f. 4; Syll. p. 
362-4. Volvaria, Thelotrematis spp., Ascidium, Ectolechia, Myrio- 
trema, Coscinedia, Brassia, Antrocarpon, & (?) Mass. Ric. p. 141; 
Alcun. gen. p. 10; Miscell. p. 88; Esam. comp. p. 12, &c. 
Apothecia urceolata, e verruceformi scutellato-aperta, disco ve- 
lato; excipulo proprio varie colorato margine sublacero cum thallino 
concreto. Spore ex ellipsoideo oblonge, bi-pluriloculares, 1. demum 
muriformi-multiloculares, fuscee 1. decolores. Spermatia fere in- 
cognita. Thallus crustaceus, unifurmis. 
T. lepadinum, Ach., the species first indicated (Ach. Z. U.) as distinct 
from Pertusaria, and attaining to its perfection in the northern hemi- 
sphere, may perhaps still be regarded as the type of the now widely ex- 
panded genus; and the character remain as it was conceived by Acharius 
(Syn.) Eschweiler, and Fries. In this species the excipular envelopes are 
in fact triple; and there is no doubt of its sufficient distinction from 
Urceolaria. But the innermost of these envelopes (veluwm Eschw.; excipu- 
lum interius, Fr.) tends manifestly to abortion; and little reliance can 
be put upon it, in its proper form at least, in the tropical groups. It 
recurs indeed here, and sometimes very elegantly expressed, as in 7. pla- 
tycarpum, Obs. Lich. ; but this species is closely associable in every other 
tespect with 7. leucastrum, of the same memoir, in which it is deficient. 
The resemblance of such abortive conditions, in which moreover the 
