442 Professor J. W. Gregory—Rotiform Bryozoa. of the Chalk. 
IV.—Tue Rorirrorm Bryozoa oF tHE Ist oF WIGHT. 
By J. W. Grucory, D.Sc., F.R.S., F.G.S. 
SMALL fossil with a wheel-shaped body borne on a narrow stem 
has long been known from the base of the Holaster planus zone 
in the Isle of Wight.. It has been recognized as one of the Bryozoa, 
but has not been described, although once recorded as ‘‘near Defrancia 
diadema, Hag.” It has also been recorded by Dr. A. W. Rowe as 
‘‘the beautiful little rotiform Bryozoon.”’” 
The following diagnosis has been lying unpublished for eight years 
in the manuscript of the second volume of the Catalogue of Cretaceous 
Bryozoa in the British Museum. A preliminary account of the species 
is now issued, as the name is wanted for reference in the course of 
Dr. A. W. Rowe’s forthcoming memoir on the Chalk of the Isle of 
Wight. A fuller account of the species with illustrations, on plates 
drawn in 1900, will be given in the Catalogue, which it is hoped will 
be issued during this Winter. 
- BICAVEA ROTAFORMIS,® n.sp. 
. Dragnosis.— Zoarium simple or compound, with a narrow cylindrical 
stem, attached in a circular concavity in the lower part of the body. 
The body of the zoarium is discoid, or wheel-shaped, and has on the 
margin a series of vertical radial projections like cog-wheels. The 
cogs usually project for a distance nearly equal to the radius of the 
disc. ‘The cogs may be prolonged at their upper, outer corner into 
spike-like fasciculi. The upper surface between the bases of the 
fasciculi is depressed, and occupied by the small, crowded, irregular 
apertures of the intermediate, subordinate zocecia. Stems appear 
solid and imperforate, as they are covered by a lamina, which is 
fluted vertically or wrinkled horizontally. Two zoaria may arise 
from one stem, or several zoaria may arise from a stolon. 
Lune B08, B.M.D. 2297. BM. D. 2296. 
Diameter of body, central disc... oo 26 3mm. 3°5-3°75 mm. 
Diameter of body, eae Proje jections.. 380 a 5, 6—7 mm. 
Length of stem... ace bak DA oe —_— 
Diameter of stem ... Ao8 seh bis sits *8-l mm. 1mm. 
Zocecia, diameter ... aus 60 she — °15—"17 mm. 
Zocecia, diameter of aperture 500 B06 ade -08 mm. -08—"1 mm. 
Number of fasciculi ass — 8-9 
Distribution.—Dr. Rowe has kindly given me the following list of 
localities. The horizon is always the base of the Holaster planus 
zone :—Dorset: Mupe Bay. Isle of Wight: Military Road, Fresh- 
water; Pit No. 138, Shaleombe Down; Pits Nos. 19 and 20, Arreton 
Down: Pit No. 37, Brading Down; Pit No. 51, Carisbrooke ; RE at 
Compton Bay and Culver Cliff. 
Affinities —The nearest allies of this species are some specimens 
from the Danian Chalk of Faxoe described as Radiopora urnula,* 
1H. W. Bristow: ‘‘ Geology of the Isle of Wight,’’ 2nd ed., 1889, p. 272. 
2 A. W. Rowe: “The Zones of the White Chalk of the English Coast.— 
II. Dorset’’: Proc. Geol. Assoc., vol. xvii, pt. 1, 1901, pp. 23, 46. 
3. Shaped like a cog-wheel. 
* Radiopora urnula, Pergens & Meunier: Bry. gar. Faxe: Ann. Soc. mal. Belg., 
vol. xxi, pp. 224-226, pl. ix, figs. 1-5; pl. x, fig. 6 
