ON THE BRITISH FOSSIL CORALS. J09 
» Spined ... superba. 
U AVY)... costata. 
—— gibbosa. 
( —— gibbosa. 
—— plana. 
minuta, 
| reptans. 
il dendroidea. 
plain : 4 { parasitica. 
$606 Jos bpoR CARE CU-COLCADL ERE =. pedunenlata. 
rudimontaryer cs. Assis. etancseee favoidea. 
| and straight... Astroccenia insignis. 
ornamented... 
The surface of the coenenchyma ...4 ridged ..............0.c0ceceeeee eee 4 
Astrocenia clavellata, Terq. et Piette, is found in the Luxembourg Lower 
Lias, but the zones above that of Ammonites angulatus in the Lias do not 
present, as yet, any species. The species is represented in the Oolites, and 
became extinct in the Falunian. 
Cyathocenia is a new genus, which I have suggested and published in 
order to admit forms which, had they been furnished with a columella, would 
have been classified as Astrocwnie. There is a species in the zone of Ammo- 
nites Bucklandi. Some of the species are mimetic of the Astrocenie. The 
following is a scheme of the genus. 
Cyathocenia. 
f branching® haying: costae. .22....:se.css.qsckeveri cus renees C. dendroidea. 
Cyathocenie with } incrusting, no costw, cenenchyma granular ......... C. incrustans, 
the corallum.... } flat large cost. and a deep calice ...02......0eece0.2. C. costata. 
( globular, no costx, coenenchyma plain.................. C. globosa. 
The gradation of structure in the genera just passed under our notice 
becomes more and more evident as such forms as those included under the 
genus Cyathoceenia are studied. In the early stage Thecosmilia cannot be 
distinguished from Monilivaltia ; but gemmation from the calice, from the 
ealicular wall, or from the wall ensued, or fissiparous division occurred, as 
the corals grew. There was an evident tendency in Montlivaltia Wallic, 
Duncan, for instance, to reproduce by calicular gemmation; but in Oppeli- 
smilia distinct calicular budding occurred. Under these circumstances the 
genetic relations of the three genera Thecosmilia, Montlivaltia, and Oppeli- 
smilia are of the closest. 
Now in bush-shaped Thecosmilie union often occurs between a bud from 
the wall and the parent stem. A section transverse to the line of growth 
shows, (1) low down, two corallites with their septa, walls, and epitheca per- 
fect; but higher up the epitheca is not seen in a section, and the walls may 
be (2) slightly separate, or (3) quite fused, and they then appear as one 
lameHa between the corallites. 
(1) is what is observed in Elysastrea; (2) is the Septastrean peculiarity ; 
(3) peculiarizes [sastrea. 
The origin of Latimeandrea from Isastrea has already been noticed. In 
Flysastrea the epitheca and one wall become absorbed at the calicular 
margin. In Cyathocenia the epitheca between the walls becomes ccenen- 
chymal, and variously ornamented ; whilst in Astrocenia the same thing occurs 
besides the growth of a columella. 
The following grouping of the genera is made with a view to assert that 
they had genetic relations with Montlivaltia, and that some Cainozoic types 
revert to more ancient. 
