118 
ME. H. N. MOSELEY ON THE 
all other Alcyonarians except Cor allium *. From both Cor allium and Tubipora, Helio- 
pora differs in that the hard tissue of its corallum shows no signs of being composed of 
fused spicules, hut in its histological structure most closely resembles Zoantharian 
Corals. With the Milleporidse and with the Pocilloporidse and Seriatoporidse Heliopora 
is allied solely on account of its possession of tabulae. Now that an Alcyonarian is 
added to the list of various Anthozoa possessing these peculiar structures, their presence 
becomes of less classificatory importance even than Professor Vekkill proved it to be. 
There can hardly be a doubt that Seriatopora will prove to be, like Pocillopora , a 
Zoantharian; and Millepora is certainly very different in structure from Heliopora. 
Heliopora thus stands quite alone amongst modern forms ; and in the peculiar structure 
of its cellular ccenenchym it is so remarkable that it is unlikely that on examination of 
the soft parts of other corals, at present known from their coralla only, any near 
relatives of it will be discovered. Amongst extinct forms, however, Heliopora has several 
close allies, and the genus itself existed in the Cretaceous period. The genus Polytre- 
macis differs apparently only in the more perfect development of the so-called septa, 
which reach to the centres of the tabulae. The genus occurs in the Chalk, Greensand, 
and in Eocene formations. Heliopora has, further, a very closely allied palaeozoic 
representative in Heliolites , in which the ccenenchymal tubes are provided with very 
closely placed tabulae. 
The three genera Heliopora, Polytremacis, and Heliolites differ from one another in 
so slight a degree that they are placed under the one genus Heliopora by Quenstedt. 
To include these three genera, a new family of Alcyonarians must be formed, for which 
the term Helioporidae appears most suitable, which family may from the recent species 
be thus characterized : — 
Family HelioporiD;E. 
A compact corallum present, composed of a ffbro-crystalline calcareous tissue as in 
Madreporaria. Corallum consisting of an abundant tubular ccenenchym, and with 
calicles having an irregular number of lateral ridges resembling septa. Calicles and 
ccenenchymal tubes closed below by a succession of transverse partitions. Polyps com- 
pletely retractile, with tentacles when in retraction introverted. Mouths of the sacs 
lining the coenenchymal tubes closed with a layer of soft tissue, but communicating 
with one another and with the calicular cavities by a system of transverse canals. 
The structure of the ccenenchym of the Helioporidae is entirely unique amongst 
Anthozoa ; no other form has a coenenchym composed thus of a series of long tubes 
packed side by side, and lying parallel to the calicular tubes and at right angles to the 
surface. It is to be remarked that the tubes are like the calicles in being open above, 
* I have found no information on this point in any of the text-books; but in Schmahda’s ‘Zoologie’ there 
is a figure of CoraUium, copied from Lacaze-Duthiess’s ‘Hist. Nat. du Corail,’ in which the tentacles are 
drawn introverted as they are in Heliopora. 
