f a living plant to the height of several inches
where the sporangia at length appear "heaped and pent", an encircling
sheath, conspicuous after the fashion of a spumaria for which it is
indeed sometimes mistaken.

6. DIDERMA LYALLII (_Massee_) _Macbr._

PLATE XVIII., Figs. 5 and 5 _a_

1892. _Chondrioderma lyallii_ Massee, _Mon._, p. 201.
1894. _Chondrioderma lyallii_ Mass., List., _Mycetozoa_, p. 81.
1899. _Diderma lyallii_ Mass., Macbr., _N. A. S._, p. 99.
1911. _Diderma lyallii_ List., sub-species, _Mycetozoa, 2nd ed._,
p. 105.

Sporangia obovate, more or less closely crowded, white, stipitate, about
1 mm. in diameter, the outer peridium firm, stout, encrusted, especially
above, with granular masses of lime, the inner well developed, more or
less cartilaginous, opaque, yellow or buff-colored; hypothallus well
developed, venulose, white, passing up unchanged to form the short,
stout stipe and lower outer peridium; columella prominent, half the
height of the sporangium, brown; capillitium of short, brown threads,
rigid, much branched, forming a net, widened irregularly and especially
at the net-nodes; spore-mass black, spores by transmitted light bright
brown, rough, 15-17 mu.

A very distinct species; large, fine, showy sporangia in more or less
crowded clusters spring from a snow-white, common hypothallus. First
reported from western Canada. Our first specimens were collected by the
late Mr. Charles Irish, on the eastern slopes of the Sierras, in Nevada;
now coming in abundantly from all the western mountains to the Pacific.

7. DIDERMA TESTACEUM (_Schrad._) _Pers._

PLATE VII., 4, 4 _a_, and 4 _b_.

1797. _Didymium testaceum_ Schrad., _Nov. Gen. Plant._, p. 25.
1801. _Diderma testaceum_ Persoon, _Syn._, p. 167.
1873. _Chondrioderma testaceum_ (Schrad.) Rost., _Vers._, p. 13.
1874. _Diderma mariae-wilsoni_ Clinton, _Rep. N. Y. Mus._, XXVI.,
p. 74.
1899. _Diderma testaceum_ (Schrad.) Pers., Macbr., _N. A. S._, p. 99.
1911. _Diderma testaceum_ Pers., List., _Mycetozoa, 2nd ed._, p. 106.

Sporangia gregarious, sessile, depressed-spherical or sometimes
elongate, small, 1 mm. or less, rose-white, smooth, the outer peridium
crustaceous, rather thick and persistent, polished, slightly raised
above the inner, which is dull ashen and more or less wrinkled;
hypothallus none; columella prominent, hemispherical in the typical
rounded forms, slightly rough, reddish or re