File:The Quarterly journal of the Geological Society of London (13860046054).jpg

52
G. E. TINE OK THE WEDLOCK POLYZOA.
Ascodictyon, Nicholson and Etheridge, jun.,
Ann. & Mag. Nat. Hist. June 1877.
Gen. Char. u Organism composite, parasitic, adherent on foreign
bodies, composed of numerous calcareous cells or vesicles, the walls
of which are perforated by a greater or less number of microscopic
foramina, but which possess no single large aperture. The cells
may be united almost directly by the intervention of short tubular
necks: or they may be disposed in clusters connected with one
another by hollow filamentous tubes, which usually anastomose, and
which, in some cases, at any rate, are likewise perforated by micro-
scopic pores "

• .

This genus was established by the authors for species found in
the Devonian formation of America and the Carboniferous of Scot-
land. I have not seen the Devonian species, and I rely on the
general accuracy of Prof. Nicholson's details with regard to these.
With our own Carboniferous species I am very familiar. Since
having the plcntitude of washed shales supplied by Mr. Maw, I have
been able to examine some hundreds of specimens on stems of
crinoids, broken shells, and corals. This circumstance has helped
me to understand and work out many biological details the narration
of which would be out of place in a general paper like the present.
I accept the genus of Prof. Nicholson and Mr. Etheridge

and,
so far as I am able at present, I give below descriptions of the
various species found within a very limited range in these shale-
washings.
Figs. 1 & 2.— Ascodictyon stellatum, Nicli. Sf Ether., var.
siluriense, Vine,
Several rosettes, showing the habit of the colonies, together with a few of the
filaments: X 24.
4. ASCODICTTOK STELLATUM, Var. SILTJEIENSE. (FigS. 1 & 2.)
Messrs. Nicholson and Etheridge characterize their Ascodictyon
stellatum as follows

—

Nicholson and Etheridge. work cited above, p.