DESCKIPTIVE REMARKS. XXV1l 
having a very similar structure, being composed of an aggregation of 
radiating tubes, and belonging to the same division Zoantharia tabu- 
lata, of Milne Edwards and Haime, flourished in the greatest profusion 
during the period of the Wenlock formation. The first of these species, 
Halysites catenularius, commencing in the Llandeilo formation, con- 
tinued on, through the intermediate formations to the Wenlock; the 
second, Heliolites interstinctus, first appearing in the Caradoc, continu- 
ing on through the intermediate formatious to the Ludlow rocks; the 
third, Favosites Gothlandicus, having the same geological range, ac- 
cording to the Table of British Silurian Fossils in Siluria, 4th ed., 
p- 510; about twenty other species of corals are recorded from the 
Caradoc formation in the same Table. ‘‘ The true corals,’”’ as Sir R. I. 
Murchison observes, ‘‘are far more characteristic of the upper than of 
the lower members of the Silurian rocks; and they are more abundant 
in them both as to species and individuals.” Léd., p. 217. 
The discovery by MM. Milne Edwards and Haime of a Palcozoie or 
ancient and Neozoic or modern type is of considerable importance ; the 
former constituting for the most part their sub-orders or divisions Zoan- 
tharia rugosa and tabulata, the latter embracing the majority of the 
Oolitic and recent species comprised in that of Zoantharia aporosa. The 
corals belonging to Z rugosa, which include the Cyathophyllide, Litho- 
dendronine, and Cystiphyllide, are characterized by having transverse 
tabule, dissepiments, and a quadrupartite arrangement of the septe into 
four, or multiples of that number, fig. 6 a. 
Fig. 6.—Palaozoic and Neozoie Type of Coral. 
PSUS 
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ee re 
In Z. tabulata, which includes Fuvosites, Heliolites, Halysites, &c., 
the tabula or dissepiments are present ; the septal arrangement is, how- 
ever, rudimentary. 
In contradistinction to these, the division 7 wporosa, which consti- 
tutes the Neozoic type, and includes the principal Oolitic and recent 
corals, such as the Zurbinolide, Oculinide, Astreide, and Fungide, the 
septal apparatus is highly developed, being composed of six elements or 
multiples of that number (fig. 6, 6); and there are no tabulz or dissepi- 
ments like those which characterize the older or Paleozoic corals. 
Crivorps are those forms of the Echinodermata, having a more or 
less globular body, composed of series of calcareous plates, from which 
