January 21, 1897] 
NATURE 
7 
a 
28 
the same radial line—to be, in short, a yree septal spine set in the 
calyx, as in the case of Paleozoic Cystiphyllids. The Triassic 
genera Stylophyllum and Stylophyllopsis show this same feature, 
also several Jurassic genera, e.g. Epistreptophyllum and Der- 
mosmilia, and there is no doubt that we have here an important 
structural feature in a living coral family which can be traced 
back to a feature characteristic of certain Paleozoic genera. 
The Eupsammids were associated by Edwards and Haime 
with the Madreporidz (sub-ord. M. Perforata). But the septal 
structure is very different. My sections prove that Turbinaria 
and Madrepora possess compact sepfa of a strictly bisymmetric 
type like those of Turbinolids, Oculinids, Stylinids. Porites 
again, the type of the other ‘‘ Perforate”’ family of Edwards and 
Haime, has a porous septum composed of radio-symmetric trabe- 
cule. The crystalline structure of the trabeculae in the Poritidze 
distinguishes them essentially from the Fungide. The homology 
of the so-called synapticula is also in my estimation different 
in Porites. I regard it as having the character of an 27/e7- 
trabecular, ¢z¢erseptal spine. It does not replace dissepi- 
mental deposit, and appears to be an ¢zhertted feature, not an 
acquired modification. 
Reasoning now upon the foundation o. the micro-structure of 
septa, I would draw the following conclusions respecting the 
classificatory system of Madreporaria. 
Proto -Zaphrentid 
Fic. 7.—Phylogenetic diagram of Madreporaria. 
(1) Septal structure affords a strong reason in favour of the 
abolition of the sub-orders Tetracoralla and Hexacoralla, since 
all the known septal types amongst Tetracorallaare also prevalent 
in Hexacoralla. 
(2) Septal structure also disannuls the groups of M. Aporosa 
and M. Perforata. Madrepora and Turbinaria, typical genera 
of the group of M. Perforata, possess compact septa, whose 
structure is the same as the septa of certain typical genera 
belonging to the M. Aporosa. Again, similarity of septal 
structure characterises compact-septate and poro-septate types | 
of Fungide ; while one and the same specimen may have some 
of its septa compact, others porous. 
(3) The two sub-families, Astraeinze and Eusmiling, hitherto 
recognised in the family of Astraeidze, have quite different types 
of septal structure. I would remove the genera of the 
Eusmilinz to various other families, ¢.g. Euphyllia and allied 
genera to the Turbinolidz ; Amphiastra and allied genera to a 
new family of Amphiastreide ; Stylina, Galaxea, &c., to a 
family Stylinidee. 
(4) The fundamental similarity in the septal type of the 
families, Madreporidze (excl. Eupsamminze, E. H.), Pocilloporidze 
(among which I would include Stylophora and _ its allies), 
Oculinidze, Stylinidz, Amphiastreide, Turbinolidz, and the 
Zaphrentidse among Palozoic corals indicates a probable 
NO. 1421, VOL. 55 | 
common ancestral line. The septal type is very simple, and 
| shows bisymmetry of design. I give it the name of Auplophractic. 
Other considerations concerning the relations of septum and 
wall, and the general habit of growth, indicate a closer affinity 
of the colony-building families, Madreporidz, Pocilloporida, 
Oculinidee, Stylinidee ; they form a natural group which I call 
Canenchymata. While the remaining three families with the 
Haplophrastic septal type are characterised by a strong wall, 
‘retaining in part or wholly its primitive character as the inner 
‘lining of the epitheca. They may be termed A/urocorallia. 
(5) The fundamental similarity in the septal type of the 
Astreide, Fungide, and the typical Cyathophyllide, the 
Eupsammide, and Cystiphyllidze, indicates an ancestral relation- 
ship of these families with one another. ‘Their septal type is 
characterised by complications due to the many pleatings of the 
septal invagination. I call it Podaplophractéc, in contradistinction 
to Haplophractic, and it will be remembered that the radio- 
symmetric trabecula attains here its full perfection, and that the 
septa are frequently porous. The families Cyathophyllide, 
Astreeide (excl, Eusmilinze), Fungidee, are characterised by the 
pre-eminence of the sefém and septo-costa in the calyx, and 
the regularity in the trabecular structure, They may be allied, 
therefore, under the name of Septocorallia. On the other hand, 
the irregularity of the trabeculae, and the occurrence of the 
detached septal spine in the radial structure, make me choose 
the name of Spinocorallia for the allied families of Cystiphyllidze 
and Eupsammidee (incl. Stylophyllinze). 
(6) The typical reef-Poritids hold, by reason of their septal 
structure, and generally of their skeleton, an isolated position 
amongst living Madreporaria. A similar position is occupied 
amongst Mesozoic corals by the Triassic family of Spongiomor- 
phide. .It seems likely that 
these two are ancestrally re- 
lated ; but I have not been able 
to do more than suggest a 
possible Palzeozoic ally in the 
Jheciidee, Provisionally, I give 
the name of Porosa to the 
Poritids and Spongiomorphids, 
in reference to the porous net- 
work of trabecular parts which 
makes up the entire skeleton. 
In summing up these points, I may say it isnot my intention to 
erect Haplophractic and Pollaplophractic sub-orders of Madre- 
poraria according to septal structure, since I know nothing in the 
nature of things to prevent the more advanced of the living 
genera whose septa aré Haplophractic in type, to attain in the 
course of evolution to the Pollaplophractic type. All the more, 
since such an evolutionary change seems actually to have taken 
place among the early Cyathophyllids. In my estimation, the 
most scientific treatment of Madreporaria is to classify them 
into families only, at the same time bearing in mind, as I 
have indicated, the close similarities existing between certain 
groups of families. My plan of Madreporarian ancestry is repre- 
sented in the accompanying diagram, and is more fully carried 
out in a phylogenetic ‘‘ scheme ” of genera given in the complete 
work (PAzl. Trans. R.S , vol. clxxxvii. (1896) p. 331) 
I have purposely devoted the greater part of the space in this 
account to septal structure ; other points can be merely indicated. 
The wall displays all the structural types just described for septa 
The structure of the ‘‘ wall” in fossil genera has an important 
bearing on questions concerning the ‘‘ Randplatte.”” (I translate 
this term as ‘‘edge-zone.”) It can be observed, for example, 
| that in the early corals the wall zs the inner lining of the 
epitheca, and the epitheca there extends up to the very lip of the 
calyx. The wall is therefore, like the tabula, primitively a one- 
sided structure. Both are laid down by continuous parts of the 
polypal ectoderm, and are skeletal forms homologous with the 
primitive inner lining of the embryonic basal skeletal plate. 
There cannot, therefore, have been any edge-zone of polypal 
flesh outside the calycinal wall of these early corals. Indica- 
tion of an edge-zone is given when the wall in fossil genera is 
seen to rise up above the epithecal mantle at the edge of the calyx. 
It is then a two-sided structure developing within a fold, as in the 
case of septa. But the two flaps of the wall-fold may be quite 
different in length, as is testified by the varying position—central 
or excentric—taken by the ‘‘ dark line” or fold-axis in the wall. 
This incoming of the edge-zone in corals took place at different 
times, and only in some genera ; in others there has never been 
an edge-zone, so far as fossil evidence goes. 
