Why, in face of so good a description, Persoon changed the name to that since current, _Tubulina_, is not clear. Fries thinks Mueller had an immature _Arcyria_ before him, _Syst. Myc._, III., p. 196. _Tubulifera arachnoidea_ Jacq., 1778, is also an uncertain quantity, insufficiently described. =Key to the Species of Tubifera= _A._ Hypothallus well developed, but not conspicuous. _a._ Pseudo-columellae none 1. _T. ferruginosa_ _b._ Pseudo-columellae present at least in many of the tubules 2. _T. casparyi_ _B._ Hypothallus prominent, columnar 3. _T. stipitata_ 1. TUBIFERA FERRUGINOSA (_Batsch_) _Macbr._ PLATE I., Fig. 4; PLATE VII., Fig. 8; PLATE XII., Fig. 14. 1786. _Stemonitis ferruginosa_ Batsch, _Elench._, p. 261, Fig. 175. 1791. _Sphaerocarpus cylindricus_ Bull., _Champ._, p. 140, t. 470, III. 1791. _Tubifera ferruginosa_ Gmelin, _Syst. Nat._, 1472 (_ex parte_). 1805. _Tubulina cylindrica_ (Bull.) DC., _Fl. Fr._, 671. 1875. _Tubulina cylindrica_ (Bull.) Rost., _Mon._, p. 220. 1894. _Tubulina fragiformis_ (Pers.) Lister, _Mycetozoa_, p. 153. Sporangia crowded, cylindric or prismatic, elongate, connate, more or less distinct above, pale umber-brown, generally simple though occasionally branched above, the peridia thin, sometimes fragile, but generally persistent, transparent, iridescent; hypothallus strongly developed, spongiose, white, often projecting beyond the aethalioid mass of sporangia; spore-mass umber-brown or ferruginous; spores by transmitted light almost colorless, plainly reticulate over three-fourths of the surface, 6-7 mu. Not rare on old logs, mosses, etc., from Maine to Alaska. Apparently more common north than south. Easily known by its long, tubular sporangia packed with rusty spores and destitute of any trace of columella or capillitium, the hypothallus explanate, rather thick, but not columnar. A single plasmodium may give rise to one or several colonies, at first watery or white, then red, of somewhat varying shades, then finally umber-brown. These colors were noticed by all the older authors, but very inaccurately; thus a white plasmodium is the basis for _Tubifera cylindrica_ (Bull.) Gmel., a roseate plasmodium for _Tubifera fragiformis_ (Bull.) Gmel., and the mature fructification for _Tubifera ferruginosa_ (Batsch) Gmel. Rostafinski adopted a specific name given by Bulliard, but Batsch has clear priority. The peridia are sometimes accuminate, and widely separate above. This is Persoon's _T. fragiformis_. In most cases, however, the peridia are connate throughout, and sometimes present above a membranous common covering. This is _T. fallax_ of Persoon; _Licea cylindrica_ (Bull.) Fries. In forms with thicker peridia, the walls often show the granular markings characteristic of the entire _Anemeae_. 2. TUBIFERA STIPITATA (_Berk. & Rav._) _Macbr._