New Species of Sponges. om 
oblique and rhomboidal in the specimens, but this is pro- 
bably due to pressure. The horizontal spicules seem to be 
triacerate in form, and much shorter than those of the ver- 
tical system, though of very different lengths. They are 
sométimes in bundles and sometimes solitary. 
In parts of the substance, apparently within the reticulate 
wall, may be seen a few cruciform spicules, and floccu- 
lent patches apparently of very small spicules, which seem 
to have been mostly internal and most abundant toward the 
base, but cannot be distinctly made out. 
The whole of the spicules are completely pyritized, and 
appear under the microscope to be made up of rows of 
cubical crystals of pyrites. They were probably originally 
siliceous, but this need not excite surprise, as the silica of 
such spicules is in a condition which facilitates solution, 
‘and in some modern sponges the spicules are not purely 
silicious, but contain some animal matter. I have also 
noticed other cases in which silicious paleozoic sponges 
have experienced this change, while in many specimens 
the spicules have entirely disappeared. 
This is the case with the Erian or Devonian sponges of 
the genus Dictyophpton and allied genera, which, owing to 
their apparently membranous character, I at one time be- 
lieved to be fucoids, but abandoned this idea on seeing the 
specimen of Uphantenia (Physospongia, Hall) which Prof. 
Whitfield was kind enough to show me in the New York 
Museum in July, 1881. In a note communicated to Prof. 
Whitfield in August, 1881, I have made the following 
remarks on the pyritization of sponges :— 
“The most puzzling fact in connection with the original 
silicious character of these sponges is their mineral condi- 
tion, as being now wholly replaced by pyrite. Carbonaceous 
structures are often replaced in this way, and so are also 
calcareous shells, especially when they contain much cor- 
neous matter, but such changes are not usual with silicious 
organisms. If the spicules were originally silicious, either 
they must have had large internal cavities which have been 
filled with pyrite, or the original material must have been 
