Reports & Proceedings—Mvneralogical Society. 575 
The corallum in this genus, as also in Phillipsastrea and in 
Orionastrea, represents a stage in colonial development in which the 
epitheca of the individual corallites has entirely disappeared, and 
these are consequently united by their dissepimental tissue—a type 
of colony to which the term ‘ Astreiform’ may be applied. 
Diacnoszs.—Aulina rotiformis.—The corallum is massive, and the 
corallites are united by their extrathecal tissue; all the septa dilate 
at the theca, and those of the major cycle again dilate at their axial 
edges, in such a manner as to fuse together, and so build a cylindrical 
wall or tube within the theca. The structure of the form is in most 
respects similar to that of Phillipsastrea, but it appears to carry 
forward the septal characters peculiar to that genus to a further 
stage of development. 
Phillipsastrea.—The corallum is composite and massive ; the 
corallites are united by their dissepiments, or are only separated by 
a thin epitheca; in the former case the septa are often confluent. 
Major and minor septa dilate at the theca; the latter terminate 
there, and the major septa attenuate and advance into the intrathecal 
region, and there often dilate again at the axialedge. The central 
part of the corallite is occupied solely by tabule. 
Orionastrea.—The characters of this genus are essentially those 
of Inthostrotion, but of a modified form. The corallum is composite 
and massive, and the corallites are either defined by a thin epitheca, 
or, in the more typical instances, by no epitheca at all; in this latter 
ease the corallites are united by their dissepiments and the septa are 
confluent. 
The distinguishing characters of the three species recognized and 
described are as follows :— 
1. O. ensifer (Edwards & Haime) . Septa not confluent. Columella present. 
2. O. phillipsi (McCoy) . . . . Septaconfiuent . . Columella present. 
3. O. placenta (McCoy) . . . . Septaconfluent . . Columellaabsent. 
II].—MrneratocicaL Society. 
Anniversary Meeting, November 7, 1916.—W. Barnow, F.R.S., Presi- 
dent, in the Chair. 
The following were elected Officers and Members of Council: President, 
Mr. W. Barlow, F.R.S.; Vice-Presidents, Professor H. L. Bowman, Mr. A. 
Hutchinson; Treasurer, Sir William P. Beale, Bart., K.C., M.P.; General 
Secretary, Dr. G. T. Prior, F.R.S.; Foreign Secretary, Professor W. W. 
Watts, F.R.S.; Editor of the Journal, Mr. L. J. Spencer; Ordinary Members 
of Council, Captain W. Campbell Smith, Dr. J. W. Evans, Dr. F. H. Hatch, 
Mr. J. A. Howe, Mr. T. V. Barker, Mr. G. Barrow, Professor C. G. Cullis, 
Mr. F. P. Mennell, Mr. H. Collingridge, Mr. T. Crook, Dr. G. F. Herbert 
Smith, Dr. H. H. Thomas. 
The following papers were read: Dr. J. W. Evans: The Combina- 
tion of Twin Operations. The question of complex twin-crystals in 
which two distinct laws of twinning are represented was dealt with. 
