Miscellaneous. 237 
On the Nature of Dictyophyton. By R. P. Wurrrierp. 
Since writing the article on Dictyophyton published in the last 
number of this journal I have obtained additional evidence of their 
spongoid character. About the middle of May, while discussing 
their nature with Principal Dawson, of Montreal, 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-glass of moderate power it is seen to 
have been composed of cylindrical threads of various sizes, now re- 
placed by pyrite. With the means then at our command it was 
impossible to fully determine whether they had been bundles of 
vegetable fibres or sponge-like spicules; but Dr. Dawson kindly 
offered to examine them more critically if I would forward a speci- 
men to him at Montreal. This was done; and his note on their 
nature is appended below. The specimen used probably belongs to 
the genus Uphantenia, Vanuxem, and is a fragment about 24 by 3 
inches across, and seems to have been a part of a circular or discoid 
frond of 8 or 10 inches diameter. It differs from Uphantenia 
chemungensis of New York in many features. The broad radiating 
bands are more distant, with a narrow 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 ad- 
joining spaces, as if the bands had been elastic, like rubber, and 
had contracted, wrinkling up the intermediate spaces. A further 
description and illustration of the form I shall defer to a future 
occasion, but shall here designate the species as Uphantenia Daw- 
sont. 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 ina radiating manner. The character 
and nature of these threads and spicules are well set forth in Dr. 
Dawson’s note below, and the spongoid features and relations to 
Euplectella indicated.—Amer. Journ. Sc., Aug. 1881. 
Note by Dr. J. W. Dawson on the Structure of a Specimen of 
Uphantenia 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 grey, finely arenaceous matrix. The spaces of the 
network are of an average size of 6 millim. in length and 4 or 5 in 
breadth. The longitudinal bands are about 3 millim. broad, the 
transverse bands much narrower. Some of the rectangular inter-- 
spaces are of the colour of the matrix, others wholly or partially 
