SUB-CLASS III ANTHOZOA—OCTOCORALLA 107 
by a fibro-crystalline calcareous matrix impregnated with organic matter. It 
is found but rarely in the fossil state, but is known from the Cretaceous and 
Tertiary. 
Family 4. Tubiporidae. Milne-Edwards and Haime. 
Coralla composed of ved-coloured parallel calcareous tubes connected by horizontul 
plates. 
The cylindrical tubes of the recent Organ-pipe Coral (Zubipora) are com- 
posed of spiniform sclerites, which are united with one another directly in such 
manner as to enclose small hollow spaces appearing superficially as pores. The 
connecting horizontal plates or floors are traversed by canals which communicate 
with the visceral chambers of the tubes by means of numerous round openings ; 
new corallites are budded from their upper surfaces. Unknown in fossil state. 
Family 5. Helioporidae. Moseley. 
Caleareous coralla, composed of two series of tubiform corallites ; the larger tubes 
(autopores) are embedded in a strongly developed coenenchyma made up of smaller 
tubes (siphonopores). Both autopores and siphonopores are closely tabulate; the 
autopores are provided with ridge-like pseudosepta, which, however, do not correspond 
numerically with the tentacles. 
The affinities of the Helioporidae with the Octocorallu were first pointed out 
by Moseley.t. The larger polyps inhabit the autopores, and are furnished with 
eight mesenterial folds and a crown of eight tentacles; while the smaller 
polyps, which are without either 

@ 
tentacles or sexual organs, are Tuam qin fal 
lodged in the siphonopores. The nN We @ ie gi j 
: : = ae iN \\ 1) Glo 
skeleton is composed of  cal- iN ee 

careous trabeculae, the same as 
in the Hexacoratla, from whose He Ti 
centres of calcification radial tig 
fibres extend outwards in caespi- ie 
tose fashion. The siphonopores HA 

multiply by intermural gemma- — 
tion, while the autopores are Heliopora Partschi, Reuss sp. Upper Cretaceous ; St. Gilgen 
formed by the coalescence and ° Wolfgangsee, Salzkammergut. _A, Corallum, née atural size. 
E 2 B, Portion of surface, enlarged. C, Polytremacis Blainvilleana, 
fusion of a number of the siphono- Reuss. Upper Cretaceous; Gosau, Salzkammergut. Vertical 
section, enlarged. 
pores. 
Heliopora, Blainy. (Fig. 191, 4, B). Corallum massive or ramose ; autopores 
with 12-25 shghtly developed pseudosepta, and embedded in a coenenchyma 
made up of smaller siphonopores ; the latter are more closely tabulate than the 
autopores. Cretaceous to Recent. 
Polytremacis, VOrb. (Fig. 191, C). Like Heliopora, but pseudosepta much 
more strongly developed, sometimes reaching nearly to the centre. Cretaceous. 
Certain Palaeozoic corals (Heliolitidae) exhibiting characters very similar to 
Heliopora are assigned to the same vicinity with the latter by Moseley, 
Nicholson, and be authors. Like Heliopora, the corallum in these forms is 
massive, and consists of larger tubes embedded in a coenenchyma formed of 
1 Moseley, H. N., Philosophical Transactions, Royal Society, vol. 166, 1877. 
