30 PROCEEDINGS OF THE AMERICAN ACADEMY. 
glabrous above, pilose on the nerves beneath: heads pedicellate in 
lanceolate-bracted corymbs: scales of the involucre biseriate, ovate, 
striate: rays 4 or 5, oblong; disk-flowers externally pubescent: chaff 
ovate, scarious, obscurely dentate at the apex: scales of the pappus 
linear-lanceolate, laciniate at the apex, shorter than the tetragonal hirsute 
achene. — Leopoldina, xxiii. 6. Zetrachyron Orizabaensis, Schz. Bip. fide 
Klatt, 1. c. — Peak of Orizaba, altitude 8,000 to 10,000 feet, Liebmann, 
no. 390. Not seen by the writers. Description translated and condensed 
from the original characterization. 
Subgenus 5. Trpnrocatea, Gray. Heads few or solitary, rather 
large for the genus: scales of the pappus 4 to 5: leaves ovate, entire, 
abrupt at the base and slender-petioled, canescent-tomentose or -tomentu- 
lose beneath. — Proc. Am. Acad. xv. 38. 
26. C. discolor, Gray, l. c. Leaves ovate-oblong, obtusish, mu- 
cronulate, glabrous above, very finely tomentulose beneath: heads about 
5 at the summits of the branches, 9 lines in diameter including the 
spreading rays: pedicels long, an inch or more in length, very finely 
puberulent or nearly smooth. — Mexico without locality, Zh. Coulter, no. 
351. <A very distinct species apparently never rediscovered. 
27. C. tomentosa, Gray, l.c. Leaves ovate, subcordate, rounded 
at the apex, densely tomentose and canescent upon both surfaces when 
young but glabrate above: heads solitary, terminal: peduncles very 
tomentose, rather stout and somewhat thickened upward. — Between san 
Luis Potosi and Tampico, Palmer, no. 1108. Not since collected. 
Species of uncertain affinities. 
28. C. sessilifiora, Less. Shrub: leaves very obtuse or. subcor- 
date at the base: heads discoid, about 10-flowered: involucre cylindrical : 
chaff broad, obovate, muticous at the apex. — Linnea, v. 158. — Mexico, 
Humboldt. A species as yet wholly obscure ; the characters are drawn 
from Lessing’s scanty description. 
