( 24 ) 
in Herb. V. d. Bosch) the smooth, North American form of Sticta 
glomerulifera (Tuckerm. ers. n. 105). 
XI.—PHYSCIA (DC., Fr.) Th. Fr. 
Th. Fr. Lich. Arct. p. 60. Stizenb. Beitr. 1. c. p. 173 (P. euploca excl.) 
Physcie spp., et Imbricarie spp., DC. Fl. Fr. Borrere spp., et Par- 
meliz spp., Ach. L.U.; Syn. Hagenie spp., et Parmelie spp., Eschw. 
Syst. p. 20. Parmelia sect. Physcia max. p., Fr. 8. O. V. p. 243; L. 
E. p. 76. Eschw. Bras. p. 194. Tuckerm. Syn. N. Eng. p. 32. Ha- 
genia, De Not. Framm. p. 7. Dimelena sect. A, et B max. p., Norm. 
Con. p.19. Physcia et Lobaria, Naeg. et Hepp. in Hepp Abbild. t. 1. 
Anaptychia, Koerb., Mass. Mem. p. 33. Anaptychia et Parmelia, 
Kkoerb. Syst. p. 49, 84. Anaptychia et Squamaria, Mass. Symm. p. 74. 
Physcia sect. A, b, et B, b, Nyl. Prodr. Gall. p. 59. Physcia sect. A, 
b, et B, c, Nyl. Syn. 1, p. 406, t. 8, f. 50, 538. Tuckerm. Physc. in 
Obs. Lich. 1. ¢. 4, p. 384. Parmelia, Anz. Catal. Sondr. p. 29. Bor- 
rera, Mudd Man. Brit. Lich. p. 103. Physcia et Tornabenia, Th. Fr. 
Gen. pp. 51, 59. 
Structuram expos. Tulasne, Mém. pp. 43, 63, 161, t. 1, f. 8-16, t. 2, 
f. 16-17; Speerschneider, in Bot. Zeit. 1854, pp. 593, 609, 625, t. 14; 
Schwendener, Untersuch.; 1. c. 2, p. 161, t. 5, f. 12-13, et 3, p. 154, t. 
8, f. 1-2, 14. ’ 
Apothecia scutelleformia. Spore ellipsoidec, biloculares [rariss- 
ime, in spp. exot., quadri-pluriloculares] fuscee. Spermatia ellipsoidea 
vel oblonga; sterigmatibus multi-articulatis. Thallus foliaceus, 
ramoso-laciniatus, stellatus, aut adscendens evernieformis, subcar- 
tilagineus. 
Differing from Parmelia in general habit no less than in essential 
characters, as Fries first pointed out, Physcia is, in the same way though 
less decidedly, separable also from Theloschistes. Schwendener has 
largely shown the contrast between the confused tissue which constitutes 
the cortical layer in Parmetia, and the well-defined parenchyma of the 
more strictly foliaceous Physcie, and the foliaceous forms of Theloschistes; 
while in his exposition of the relative thickness of the same layer, this 
writer has also explained what is no doubt the prigcipal cause of the pal- 
pable difference between the more membranaceous thallus of Parmelia, 
and the more cartilagineous one of Physcia. It is, however, in its rela- 
tions to Theloschistes that the group before us, typically indeed Parme- 
liine, but exhibiting a more evident tendency to pass into ascendant 
states than Parmelia, is especially interesting. Physcia ciliaris and 
Speciosa are to P. stellaris exactly as Theloschistes chrysophthalmus to 
T. parietinus; and this is the same as to say that the modifications of 
thalline structure (Schwend. 1. ¢. 3, p. 155) which should confirm the 
