PALEOZOIC TYPES OF MADREPORARIA. 
37 
The discovery of the rugose Holocystis elegans , Lonsd. sp., in the Necomian has already 
been noticed ; it is a species which belongs to the same family as Stauria and Conos- 
milia. 
M. de Fromentel has arranged many genera of Secondary and Tertiary corals according 
to their septal types ; and he notices that a doubtful generic title is given to Bimorpho- 
coenia corallina by Etallon, and that the form which belongs to the Middle Oolite coral- 
fauna is one of the Rugosa. The other species of the genus, and which is the type of it, 
has the hexameral septal arrangement, and is a Neocomian fossil. 
The same author notices and describes Pleurostylina corallina from the Middle Oolite, 
and proves that, with the normal Neozoic hexameral septal type, it has a relic of the 
rugose structure in a large septum which passes into the axial space. 
Stephanocoenia is a genus with existing Lower Cretaceous and Middle Oolite species 
having the hexameral septal type ; but there are other species found in the Eocene and 
in the Lower Chalk which have the octomeral arrangement. 
Styloccenia has species with a pentameral type in the Eocene and Lower Cretaceous 
deposits, and some with the octomeral septal arrangement in Eocene and Miocene 
strata*. 
Stylinah&s species with the hexameral arrangement in the Upper, Middle, and Inferior 
Oolites, and others with the octomeral in the Middle Oolite and Lower Chalk ; moreover 
it has species in the Trias and Middle and Inferior Oolites which have the decameral 
septal type. 
Cryptoccenia has hexameral types in the Neocomian and in the Middle and Inferior 
Oolites ; but the Middle and Inferior Oolitic strata contain species of it with the octo- 
meral septal arrangement. 
Goniocora affords examples of hexameral species in the Upper and Middle Oolites and 
in the Lias, whilst there is an octomeral type in the Middle Oolitic rocks. 
Astrocoenia has hexameral species in the Eocene and Neocomian deposits, octomeral 
in the Lower Cretaceous and Middle and Upper Oolitic strata, and in the Tertiaries of 
Castel Gombertof; but all the species described by me from the lowest Liassic strata 
possess the decameral type. The lowest coralliferous secondary deposits of Great 
Britain contain badly preserved fossils, and yet the Thecosmilian from the White Lias of 
Watchet and the cast of a congeneric form from that of Sparkfield have very rugose 
characters J. The Thecosmilice from the “Guinea bed” at Binton (zone of Ammonites 
planorbis ) have the great septum and thin wall of many Rugosa § ; and the species of 
Oppelismilia from the next and higher zone of Ammonites angulatus has no distinct 
septal arrangement, but a thick epitheca and calicular gemmation. The great Astrocce- 
nian fauna of the zone is composed of twelve species, all of which have the decameral 
septal arrangement, and none of them the hexameral. Many of the Montlivaltice of 
the zone are so irregular in their development that they cannot be classified under any 
* Reuss, Castel Gomberto, Foss. Anthoz. Kaiser. Akad. der Wissen. Wien, 1868. 
t Reuss, op. cit. + P. M. Duncan, Pal. Soc. Load. vol. xxi. p. 67. § Id. p. 66. 
