MADREPORA. 23 
3. Axial corallites slender, elongate, cylindrical ; margin plane or suddenly 
contracted, not rounded. Wall thin butdense. A second cycle of septa 
HE} TOL Ot Sale SEM RRR re GH bolo a'b Sad cb 0.50 CO ola Bee ae eae ae ae TracHyLopora, p. 184. 
Drviston [V.—Axial corallites more or less distinctly compressed, giving rise to flattened branches, 
with the most prominent corallites confined to the lateral margins. 
Disticyocyatuvs, p. 192. 
Division I. 
1. Subgenus EUMADREPORA. 
This section of the genus includes the majority of the arborescent species, together with 
others in which the origimal ramose condition is lost by fusion of adjacent branches. The 
species of the cyclopea group form massive lobes or plates; but the characters of the axial 
and radial corallites show an affinity to M. muricata f. palmata. Unless the branches 
are confluent quite to the apex the axial corallites are 2°5 mm. exsert or more. The radial 
corallites are rarely immersed on the distal divisions of independent branches, and the form 
varies from nariform either through tubo-nariform to tubular, or through half-tubular to 
labellate and dimidiate. The axial corallites possess a star of 12 septa, of which the pri- 
maries are subequal. In the radial corallites there are also usually 12 septa, unless in young 
corallites; but the directive septa are generally more prominent than any of the others. 
Corallum usually reticulate in section. A number of slender arborescent species have been 
provisionally included in the first section of the subgenus which show an affinity with the 
tubigera group referred to Polystachys. The subgenus is also related through M. crassa to 
the nobilis group of Tylopora, and to Lepidocyathus and Odontocyathus through the pocillifera 
group. 
A. Prominent corallites subequal, nariform or tubo-nariform, more rarely some are labellate. 
The radial corallites rarely bear buds unless in situations which indicate new out- 
growths. 
a. Corallum arborescent ; branches terete, rarely coalescent, but in one variety of M. muricata 
become fused together into plate-like or vasiform specimens. 
* Branches over 1 cm. diameter. 
1. Madrepora muricata. 
Millepora muricata (part.), Linneeus, Syst. Nat. ed. x. p. 792. 
Madrepora muricata (part.), Linneus, Syst. Nat. ed. xii. p. 1279; Pallas, Elenchus Zooph. p. 327 ; 
Ellis & Solander, Zoophytes, p. 171; Esper, Pflanzenth. Fortsetz. Th. i. pp. 45-59, pls. 1., li., 
liii. ?, liv. 8 ?, Lxxxiii. 
? Madrepora plantaginea, Duchassaing (non Lamarck), Anim. radiaires d. Antilles, p. 17. 
A, Forma patmata. 
Madrepora muricata, var., Esper, loc. cit. pls. li., Ixxxiii., liv. B? 
Madrepora infundibuliformis, Esper (non Linn.), loc. cit. pl. li. 
