1882. ] MR. S. 0. RIDLEY ON THE CORALLIIDE. 231 
lateral small branches on the sides of the large ones, the antero- 
posterior flattening, the rigidly anterior position of the verruce of the 
general surface, their abrupt projection and truncate extremity, 
separate it from all other species ; while the minute characters, such 
as the double spicular complement, with its very remarkable form 
no. ii-—absent as it is from two of the recent Coralliide in which the 
spicules are known, and approximating the genus (as it appears to me 
to do) to the Melitheide, from its resemblance to the “ Blattkeule ”’ 
so widely distributed in that family—unmistakably show its true 
position to be by the side of Pl. johnsoni. The chief differences 
between the species are the red colour of the greater part of the hard 
axis and of the cortex, the absence of the terminal tubercles to the 
cylindrical spicule no. i., and the smaller size of the verrucze, in the 
present form. 
Key to the Genera, Species, and Varieties. 
I have here endeavoured to present what appears to be the natural 
relations of the different forms, while giving characters which may 
readily distinguish them. 
I. Spicules of one kind, viz. octoradiate cylindrical. Ver- 
ruce distributed over whole surface of corallum, promi- 
nent, Monticular ..........cseseeeeeereeeees CoRALLIUM 8. str. 
1. Corallum branching in more than a single plane. 
i, Axis cylindrical; spicules about ‘09 mm. wee Known habitats. 
ety C. nobile, Mediterranean ; 
a. Axis crimson, cortex red ......... typical form, } Cape Verd Isl. 
B. Axis and cortex yellowish- { C. nobile, Medit 
white to White ......ccceceseeneeees { pale yar. } re ig 
( Fossil: Tertiaries 
of Italy and 
Scinde ; not 
earlier than 
Miocene. 
ii, Spicules ?; axis pale .............-- { ie 
2. Corallum branching in but one plane, calicles sunk in 
pits in axis. 
Axis oval in transverse section, white ; 
spicules about ‘06 mm. long; 
cortex very pale orange, very thin C. stylasteroides. Mauritius. 
II. Spicules of two kinds, radiate cylindrical and opera-glass- 
shaped ; calicles rising abruptly, truncate, those of stem 
and main branches confined to anterior surface. Corallum 
with lateral pinne to main branches. Axis oval in 
transverse section........- PLEUROCORALLIUM, Gray, emend. 
1. Axis partly red, partly white; cortex scarlet. 
i. Calicles chiefly on lateral pinne ... PZ. secundum)...‘ Sandwich Is. ?” 
ii. Oalicles chiefly on main branches ; 
cylindrical spicules normally 6- 
PAGIALO .cnenoresasiacnans +¥aselayeeccas { 
2, Axis white, cortex cream-coloured ; 
cylindrical spicules normally 8- 
BAAD +5) xisape2ccms) ache geese teense Pl, johnsoni ...... Madeira. 
III. (incerte sedis). Oorallum with branches ¢ cy ,41};4 | Fossil; White 
anastomosing, apices nodose ,.......-...++. { beokit Socal Chalk of Faxde. 
Pl. secundum, 
var. elation. } Japan? 
