306 
ADDENDA ET COKKIGENDA. 
by multilamellar tissue. The axial group is usually from 
2 to 3 rnm. in diameter. Most of the multilamellar zone is 
considerably thicker than the axial bundle, and is traversed 
by prolongations of the axial zooecia as long sinuous tubes. 
The surface of the zoarium is covered by irregularly dis- 
tributed apertures, eacli surrounded by a slightly raised 
peristome. The maculte are irregularly arranged, .and one 
line of them occurs between adjacent apertures. 
Distkibdtion. 
Lower Greensand (Aptian) : Shanklin, Isle of "NVight. 
Upper Perna Bed 1»ase of Athertield Clay) : 
Atherfield, Isle ot Wiglit. 
F IGTJEES. 
PL Y. Pig. \i)a, a zoarium from the side ; nat. size. Pig. lOi, 
part of the surface of the same specimen; x 9 dia. Pig. lO^?, 
a thin transverse section from the same ; X 8 dia. Lower Green- 
sand (Aptian) : Shanklin, Isle of Wight. M. Norman Coll., 
D. 3141. 
ArriNiTiES. 
This species is the type of the genus. It was originally referred 
to Heteropora owing to its apparently dimorphic character. It was 
described in great detail by Lonsdale in 1849, and though he 
considered its affinities to Heteropora , he concluded that it was one 
of the Anthozoa and not a Bryozoan. Milne-Edwards & Haime in 
1850 repudiated it as a coral, but Lonsdale rediscussed the matter 
in 1851 and stoutly maintained his previous conclusion. There can 
be no doubt, however, that Edwards & Haime were right. 
The main difficulty in dealing with the species is to determine 
whether such a form as D. 3147, shown on PI. Y. Figs 10^7, J, is 
simply the central axis of Choristopetaliim, or whetlier it belongs 
to a distinct genus. I have come, however, . to the hesitating 
conclusion that the specimen thus figured is the central part of 
a Choristopetalum. 
LIST OF SPECIMENS. 
46,801. The tvpe-speciiueu and sections. Lower Greensand. Atherfield. 
Figd. Quai-t. Journ. Geol. Soc. vol. v. pi. iv. figs. o-ll. 
D. 3146. Three fragments and two thin sections of stem. Lower Greensand. 
Shanklin. Norman Coll. 
1 D. 3147. Part of a zoarium without the external multilamellar layers. Lower 
Greensand. Shanklin. Figd. PI. Y. Fig. 10. 
