CORALS FROM THE GREAT OOLITE. 119 
to which latter species it has been referred by Prof. M‘Coy. It differs, however, from C. 
afinis by its septa, which in the latter are much more unequal in height as well as in thick- 
ness, and form generally three complete cycla. In 7. dendroidea the branches are more 
cylindrical, and vary much less in diameter ; the septa are thicker, strongly denticulated, and 
do not appear to have any paliform lobules. 7. cadomensis' and C. Waltoni? are equally 
of an arborescent form, but in the former the septa are thin, flexuous, and become united 
by their inner edge ; and in the latter the aspect of the calice is quite different, on account of 
the septa being thick towards their external edge, and on the contrary very thin inwards. 
2. THamnastreA MAMMOoSsA, Tab. XXIII, figs. 3, 3a. 
Corallum massive, tall, subpyriform, terminated by a mammose surface, and composed 
of superposed layers, which are intimately united, and most distinct near the basis. 
Calices small, placed at unequal distances, and often disposed in a radiate order towards 
the summit of the mammillary protuberances. Fossw/a well characterised, but not deep, 
and containing a small tubercular columella. Sixteen or eighteen septa, somewhat 
unequal and rather thin ; some smaller than the rest, are placed irregularly, the others are 
straight, or bend towards their outer edge, where most of them join the corresponding 
one from an adjoining corallite. Diameter of the calices, half a line. 
This fossil belongs to the collection of Mr. Stokes, and appears to have been found in 
the Great Oolite at Sapperton, in Gloucestershire. 
7. mammosa differs from most species of the same genus by the small size of its 
calices, its strongly gibbose surface, and its mode of growth by superposed layers. It 
3 
most resembles 7. scita,’ 7. tenuissima,* and T. concinna,’ but its septa are more equally 
developed than in the latter, and are much Jess numerous than the first two. 
3. THamnastrea scita, Tab. XXIII, figs. 4, 4a. 
Corallum massive, terminated by an almost flat surface, and composed of thin super- 
posed layers, the uppermost of which are often incomplete. Calices small, almost equally 
dispersed, and shallow; fossula small; columella rudimentary. Seta delicate, closely 
set, and differmg somewhat in thickness and in breadth alternately; they are very 
unequally confluent, and some are straight, whereas others are flexuous or strongly 
geniculated ; their lateral surfaces appear to be delicately granulated. Diameter of the 
corallites about three quarters of a line. 
1 Astrea cadomensis, Michelin, Ieonogr., tab. liv, fig. 4. 
2' Tab. xxix, fio. 4. 8 Tab. xxiii, fig. 4. 
Synastrea tenuissima, Milne Edwards and J. Haime, Ann. Sc. Nat., 3d ser., vol. xii, p. 191. 
- 
on 
Tab. xviii, fig. 3. 
