132 Whitfield and Dawson—Nature of Dictyophyton. 
Art. XXIIT.—On the nature of Dictyophyton; by R. P. Wurr- 
FIELD. With a note, by J. W. Dawson. 
_ SINCE writing the article on Dictyophyton published in the 
last number of this Journal I have obtained additional evi- 
dence of their spongoid character. About the middle of May, 
while discussing their nature with Principal Dawson, of Mon- 
treal, we examined some allied forms from the Keokuk beds at 
Crawfordsville, Indiana, which lately came into the possession 
of the American Museum of Natural History, and found one 
which retained the substance of the organism. Under a hand- 
lass of moderate power it is seen to have been composed of 
cylindrical threads of various sizes, now replaced by pyrite. 
ith the means then at our command it was impossible to 
fully determine whether they had been bundles of vegetable 
fibers or sponge-like spicules; but Dr. Dawson kindly offered 
to examine them more critically if I would forward a specimen 
to him at Montreal. This was done, and his note on their na- 
ture is appended below. The specimen used probably belongs 
to the genus Uphantaenia Vanuxem, and is a fragment about 
24 by 3 inches across and seems to have been a part of a circu- 
lar or discoid frond of 8 or 10 inches diameter. It differs from 
Uphantaenia Chemungensis of New York in many features. 
The broad, radiating bands are more distant, with a n«rrow, 
_ thread-like band between; while all the circular bands have 
been narrow or thread-like. The spaces between the bands 
and threads are rectangular and covered by a thin film which 
is alternately elevated or depressed in the adjoining spaces, as 
if the bands had been elastic like rubber and had contracted, 
wrinkling up the intermediate spaces. A. fnrther description 
and illustration of the form I shall defer to a future occasion, 
but shall here designate the species as Uphantaenia Dawson. 
The broad bands are composed of very fine thread-like spicules, 
and the narrow ones of much stronger ones, while the thin film 
occupying the intermediate spaces is composed of still smaller 
spicules apparently arranged in radiating manner. The char- 
acter and nature of tiese threads and spicules are well set forth 
in Dr. Dawson’s notes below, and the spongoid features and 
relations to Huplectella indicated. 
° 
Note by Dr. J. W. DAWSON on the Structure of a specimen of 
Uphantaenia, from the Collection of the American Museum of 
Natural History, New York City. 
To the naked eye the fossil presents rectangular meshes of 
dark matter on a gray finely arenaceous matrix. The spaces of 
the network are of an average size of 6™ in length and 4 or 5 
