168 ~ Miscellaneous. 
but would rather indicate a substance of considerable rigidity and 
firmness of texture. 
In examining the structure of Huplectella it is found to be com- 
posed of longitudinal and horizontal bands similar to those above 
described, with the additional feature of sets of fibres passing in 
each direction obliquely across or between the longitudinal and 
horizontal sets, but not interwoven with them ; so that the longitu- 
dinal series forms external ribs extending the length of the sponge, 
and the horizontal series inside ribs or bands; and they appear as 
if cemented to each other at their crossings. The oblique threads, 
besides strengthening the structure, cut across the angles of the 
quadrangular meshes formed by the two principal sets of fibres, and 
give to them the appearance of circular openings, making the struc- 
ture much more complicated than in Dictyophyton. ‘The addition of 
oblique fibres in Huplectella is the most noticeable difference between 
the two forms; but if placed horizontally and longitudinally be- 
tween the primary sets they would produce precisely the structure 
seen in Dictyophyton. 
As yet we have no positive evidence of the nature of the substance 
which composed the fibres in Dictyophyton. The only cases known, 
so far as I am aware, of the preservation of the substance of the 
fossil are that mentioned above, where the space between the matrix 
and the cast is occupied by a ferruginous body, a material which so 
often replaces siliceous organisms in a fossil state, and specimens of 
D. Newberryi from Richfield, Ohio, on which there occur slight 
patches of a carbonaceous substance, but not sufficient to warrant 
the conclusion that it ever formed a part of the structure, even in 
the opinion of the author of the genus, who supposed these organisms 
to have been of vegetable origin, especially as they are associated 
with numerous fragments of terrestrial plants. I am therefore led 
to the opinion, from their firmness of texture, as evinced by the 
strong markings left in the rock and the almost perfect retention of 
their original form, that they were of a siliceous nature. Still in 
this opinion I may be mistaken, and it must be left for future dis- 
covery to determine ; but that they were of the nature of sponges 
and not of plants I feel very confident. 
The form given by Professor Vanuxem in the Geological Report 
of the Third District of the New York Survey, and also figured in 
the Sixteenth Report above cited, I think would also better conform 
to this idea than to that of a vegetable origin, although its broad 
flattened bands may be something of an objection. 
The name Hydnoceras was originally applied by T. A. Conrad to 
designate a species of this genus (Journ. Acad. Nat. Sci. Philad. 
vol. vill. Ist series, p. 267), but was discarded on account of its 
objectionable signification, though, if the view here suggested prove 
correct, the later appellation is almost as objectionable-—Amer. 
Journ. Sci., July 1881. 
