knowlton] TERTIARY PLANTS OF NORTH AMERICA. 231 
Thyrsopteris microloba alata Font. Potomac Fl., p. 140, pi, lv, f. 
5; Iviii, f. 1, 1889. 
Potomac formation: Fredericksburg and near Dutch Gap Canal, 
Virginia. 
Kootanie: Great Falls, Montana. 
Thyrsopteris microphylla Font. Potomac Fl., p. 131, pi. xlv, f. 1, 
2, 4, 5, 1889. 
Potomac formation : Fredericksburg and near Potomac Run, Vir- 
ginia. 
Thyrsopteris nana Font. Potomac Fl., p. 141, pi. lvi, f. 4, 8, 1889. 
Potomac formation: Fredericksburg and near Dutch Gap Canal, 
Virginia. 
Thyrsopteris nervosa Font. Potomac Fl., p. 122, pi. xxv, f. 4, 5, 16; 
xxxvii, f. 2, 4; xxxix, f. 5; xl, f. 6, 1889. 
Potomac formation : Fredericksburg and near Potomac Pun, Vir- 
ginia. 
Thyrsopteris obtusiloba Font. Potomac Fl., p. 14.3, pi. Iviii, f. 7, 10, 
1889. 
Potomac formation: Dutch Gap Canal and near Potomac Pun, Vir- 
ginia. 
Thyrsopteris pachyphylla Font. Potomac FL, p. 135, pi. 1, f. 3, 1889. 
Potomac formation: Near Potomac Run, Virginia. 
Thyrsopteris pachyrachis Font. Potomac Fl., p. 132, pi. xlvi, f. 3, 
5; xlvii, f. 1, 2; xlix, f. 1, 1889. 
Potomac formation: Fredericksburg, near Potomac Run, and near 
Dutch Gap Canal, \ T irginia. 
Thyrsopteris pecopteroides Font. Potomac Fl., p. 135, pi. li, f. 1, 
1889. 
Potomac formation: Fredericksburg, Virginia. 
Thyrsopteris pinnatifida Font. Potomac Fl., p. 136, pi. li, f. 2; liv, 
f. 4, 5, 7; lvii, f. 7, 1889. 
Potomac formation : Fredericksburg, Virginia. 
Thyrsopteris rarinervis Font. Potomac Fl., p. 123, pi. xxvi, f. 6, 7; 
xliii, f. 4-6; xliv, f. 1, 2, 5; xlix, f. 2; clxix, f. 6, 7, 1889. 
Potomac formation : Fredericksburg, near Brooke, White House 
Bluif, and Trents Reach, Virginia. 
Knoxville beds: Tehama County, California. 
Kootanie: Great Falls, Montana. 
Thyrsopteris retusa Font. Potomac Fl., p. 144, pi. lix, f. 10, 1889. 
Potomac formation: Near Potomac Run, Virginia. 
Thyrsopteris rhombifolia Font. Potomac Fl., p. 138, pi. lii, f. 5; liv, 
f. 1, 1889. 
Potomac formation : Fredericksburg and near Dutch Gap Canal, 
Virginia. 
Thyrsopteris rhombiloba Font. Potomac Fl., p. 144, pi. lix, f. 7; lx, 
f. 8, 1889. 
Potomac formation: Near Potomac Run, Virginia. 
