A. Capillitial threads transverse to the sporangial cavity, attached usually at each end, plain or only slightly roughenedDianemaceae
B. Capillitium plain, papillose, or spinulose, often scanty, not netted, the threads sometimes attached by one end to the sporangium wallPerichaenaceae
C. Capillitium a distinct net, usually attached below to the sporangial wall; sculpture various, not continuous spiral bandsArcyriaceae
D. Capillitial threads transverse, fascicled, attached at both ends, but sculptured by well defined spiral bandsPrototrichiaceae
E. Capillitial threads typically free, sometimes more or less branched, forming a loose net attached below, characterized by definite spiral bands, or sometimes by scattered ringsTrichiaceae

A. DIANEMACEÆ

Key to the Genera of the Dianemaceæ

A. Capillitial threads attached at one end, or free1. Margarita
B. Capillitial threads attached at each end2. Dianema

1. Margarita List.

Sporangia sessile, the capillitium simple, hair-like, coiled.

1. Margarita metallica (Berk. & Br.) List.

[Plate XVII]., Figs. 1, 1 a, 1 b.