w, smooth; capillitium
centrally attached, when fresh, brick-red in color, fading on exposure,
the threads of uneven size, those above 6-7 mu, below 3 mu, abundantly
branching, marked by conspicuous reticulations formed by the
intersection of numerous vertical plates or ridges; spore-mass reddish,
spores by transmitted light pale ochraceous, distinctly warted, 10-12 mu.

This species is distinguishable at sight by the peculiar color and form
of the sporangia. Mr. Durand in _Bot. Gaz._, XIX., pp 89, 90, gives a
careful study of the form. The same author declares the dehiscence
circumscissile. We cannot distinguish _A. aurantiaca_ Raun. from the
present form.

Rare. Maine, New York; Monterey, California.

8. ARCYRIA DENUDATA (_Linn._) _Sheldon._

PLATE II., Figs. 5, 5 _a_.

1753. _Clathrus denudatus_ Linn., _Syst. Nat._, 1179.
1794. _Arcyria punicea_ Pers., _Roem. N. Mag. Bot._, I., p. 90.
1895. _Arcyria denudata_ (Linn.) Sheld., _Minn. Bot. Studies_,
No. 9, p. 470.

Sporangia crowded or gregarious, ovoid or short cylindrical, tapering
upward, red-brown, stipitate; peridium evanescent except the plicate
calyculus; stipe about equal to the expanded capillitium, concolorous,
plicate or striate, ascending from a small hypothallus; capillitium
attached to the whole inner surface of the calyculus and connate with
it; hence not deciduous, bright red or carmine when fresh, turning brown
or paler with age, the threads even, about 3 mu adorned with a series of
rather distant cogs or half rings, which form around the thread a
lengthened spiral; spore-mass red or reddish brown, spores by
transmitted light colorless, nearly smooth, 6-8 mu.

This species is easily distinguished from all other of similar tints by
the attachment of the capillitium. In this respect it corresponds with
the following species. In the adornment of the threads it is like _A.
incarnata_. It is by far the commonest species of the genus, and
probably enjoys a world-wide distribution. To be found at all seasons on
the lower side of fallen sticks, _Populus_, _Tilia_, etc.

Micheli, Pl. XCIV., shows that he had the present species. The
description given by Linne is worthless, but helped out by Micheli, and
several other authors of the eighteenth century, who take the trouble to
describe the species, but still give the Linnean binomial as a synonym;
we may give Linne here the credit. As a matter of fact, Batsch under
_Embolus crocat