220 
SILUKIA. 
[Chap. X. 
the Zoantharia tabulata of M.-Edwards and Haime, to which the Thecidae, the 
Favositidae, and the Milleporidae belong. 
The Palaeocyclus of Milne-Edwards was considered by that naturalist to be- 
long to the family Fungidae, which includes the modern Mushroom- corals, and 
was supposed to be the only Silurian (or, indeed, Palaeozoic) form of the group 
Aporosa* — that group which is the most prevalent in modern seas. Palaeocyclus 
porpita, Linn. (Cyclolites lenticulata, Sil. Syst.), is the one figured, Foss. 53. 
f. 3, 4 j and there are other species, P. praeacutus, Lonsdale, and P. rugosus, 
M.-Edw., in the Wenlock rocks at Dudley. 
All the Cup-shaped Corals of the Palaeozoic series, of which about fifty species 
occur in Silurian rocks, belong to the section Zoantharia rugosaf, distinguished in 
general, like the other great group (Z. tabulata), by the development of the trans- 
verse plates or tabulae in the body of the Coral (see the following woodcut), and 
including both simple cup-like forms, such as Omphyma subturbinata, Foss. 54. 
f. 4, Cystiphyllum Siluriense, f. 7, Petraia bina, Foss. 53. f. 7, 8 — and branched or 
Fossils (54). Cup-corals of the Wenlock Limestone. 
1. Cyathophyllum articulatum, Wahl. (caespitosum, Sil. Syst.). 2. C. truncatum, 
Linn. (Cyathoph. dianthus, Sil. Syst.) ; and a single cup, with its marginal disk-buds 
attached. 3. Strephodes vermiculoides, M'Coy. 4. Ompliyma subturbinata, D'Orb. ; 
and a view of the cup with its four basal pits. 5. A longitudinal section. 6. Acervu- 
laria ananas, Linn. ; and a cup, natural size, with four young buds. 7. Cystiphyllum 
Siluriense, Lonsdale. 8. C. cylindricum, Lonsdale. 
composite forms, Cyathophyllum articulatum, Foss. 54. f. 1, and C. truncatum, 
f. 2. When such compound Corals have grown closely together, so that the 
separate corallites or cups press one another into angular forms, masses are pro- 
duced, such as Acervularia ananas, f. 6, and Arachnophyllum typus, Foss. 53. f. 6. 
The latter is now called Strombodes by Milne-Edwards and Haime. 
Among these common species, two are remarkable for the mode of propagation 
of their buds or young corallites. 
In Cyathophyllum truncatum, Linne (C. dianthus, Sil. Syst.) just quoted, the 
young buds take their origin from the inner edge of the parent polype-cup 
(Foss. 54. f. 2), and the young Corals thus produced quite overtop, and at length 
cover over the parent, until in their turn they, too, produce their young clusters 
* Kecent investigations by Dr. Martin Duncan Aporose Corals to the Mesozoic and Ceenozoic 
and Dr. LindstrSm nave, however, determined this periods. 
Coral to belong to the Kugosa, thus restricting the t See Note, p. 221. 
