VINE : yuRKSHlRE CARBONIFEROUS AND PERMIAN POLYZOA. 195 
1883- 4. Rhabdomesoii gracilis (error), Vine, Ibid, p. 174. 
1884- 5. ,, gracile, Vine, Naturalist, p. 66, and 1885, p. 317. 
1885. „ ,, Vine, Trans. Yorks. Geol. Soc, vol. ix., 
p. 23, pi. X., fig. ii. 
Zoarium rod-like, slender, cylindrical and branching. Branches 
coming off at right angles to the stem, and never less than an inch 
apart. Stem consisting of a hollow axis formed by a thin calcareous 
tube, and of a series of cells ranged round the axis. Zocecial aper- 
tures (vestibule) oval, surrounded by tuberculated ridges, which bear 
two blunt spines, one on the upper and the other on the lower angles 
of each aperture. Zocecia conical, consisting of two parts, the vesti- 
bule and the cell proper. 
Range in British Rocks : (Devonian, Pilton beds ? Phillips). 
Carboniferous : — Yorkshire : Hurst and Richmond ; Derbyshire : 
Castleton ; Wales : Llangolen and Holken, rather rare : North 
Lancashire : Holker Park, Gleaston Castle, and Little Urswich : 
Northumberland : fairly abundant. Scotch Carboniferous Shales, 
Upper and Lower, very abundant. 
This very widely distributed and abundant species has been, so 
far as the structure is concerned, very fairly described by the Messrs. 
Young, and by myself in the various papers already referred to. Up 
to the present time, although some thousands of examples have passed 
through my hands, I have never met with a single specimen bearing 
an ovicell, or any other indication of a reproductive cell. This is the 
more remarkable as ovicells have been found on examples of R. 
rhomhiferum. 
In my paper on the Polyzoa of the Gayton boring, Northampton, 
I have expressed a doubt as to whether the Millepora gracilis of the 
Pilton beds really belong to the Rhabdomeson group. To try and 
settle this question I wrote to Mr. Hall, whose paper on the Pilton 
beds was quoted by me, in the hope that I might get from him ex- 
amples of the true Pilton form. This I failed in, but he referred me 
for examination to a complete series of the fossils which he had sent in 
to the British Museum. Recently I have, through the kindness of 
Mr. E. B. Newton, of the Brit. Mus., Cromwell Road, Kensington, 
examined the Townsend Hall collection of the Pilton fossils, but I 
