This curious form, with its spirally sculptured capillitial threads attached at both ends, stands intermediate between _Dianema_ and _Hemitrichia_ and _Trichia_. Berkeley called it a trichia, ignoring the attachment of the threads. Cooke notes this as sufficient to exclude the form from the genus. But it remained for Rostafinski to make the transfer by setting up for its reception the genus now adopted. He preferred the later (1866) specific name as more descriptive. Miss Lister reverts to the earlier name with the remark; "Little now remains of the type _Prototrichia metallica_ Berk. from Tasmania; but the specimen is referred to _Prototrichia flagellifera_ by Rostafinski who saw it in good condition." Not uncommon in the abietine forests of the West. Alberta, Oregon, Washington, California, Nevada, Montana, Idaho, Colorado. _E._ TRICHIACEAE Capillitium marked by spiral bands, sometimes scattered rings, etc., the threads entirely free, or at least loosely branched, and with free tips more or less numerous. =Key to the Genera of the Trichiaceae= _A._ Capillitium threads long, generally united to form a loose net, centrally attached. _a._ Sculpture spiral 1. _Hemitrichia_ _b._ Sculpture reticulate 2. _Calonema_ _B._ Capillitial threads shorter, entirely free, though sometimes branched. _a._ Threads, elaters, marked by spiral bands 3. _Trichia_ _b._ Sculpture irregular or wanting 4. _Oligonema_ =1. Hemitrichia= _Rost._ 1829. _Hemiarcyria_ Fries, _Syst. Myc._, III., p. 183 in part. 1873. _Hemitrichia_ Rost., _Versuch_, p. 14. Capillitium a tangled net of more or less branching and anastomosing fibres centrally attached; the sculpture regular, of conspicuous spirally winding bands or ridges; habit and color various. The species here associated are intermediate between _Arcyria_ and _Trichia_, resembling the former in the capillitial net and the latter in thread-sculpture. Fries applied the name _Hemiarcyrieae_ to a group of trichias so-called, citing _H. rubiformis_ as the first. In his _Versuch_ Rostafinski wrote _Hemitrichia_ and afterward _Hemiarcyria_ in the _Monograph_. Massee combines the genera _Arcyria_ and _Hemiarcyria_ under the former name. =Key to the Species of Hemitrichia= _A._ Plasmodiocarpous _a._ Plasmodiocarp net-like, yellow 1. _H. serpula_ _b._ Imperfectly plasmodiocarpous, brown 2. _H. karstenii_ _B._ Sporangia all distinct. _a._ Sessile; very short stalked i. Peridium hyaline, iridescent 3. _H. ovata_ ii. Peridium opaque 10. _H. montana_ _b._ Stipitate, generally distinctly so; sometimes nearly sessile. i. Yellow or ochraceous. O Stalk hollow. + Small, 1/2 mm., iridescent 6. _H. leiocarpa_