INTRODUCTION. ix 



Stjb-class 1. 

 CORALLABIA. 



Actinoidea, Dana. Op. cit., p. 16, 1846. 



Polypi possessing distinct internal reproductive organs, and having the gastric or 

 visceral cavity surrounded by vertical, radiating, membranaceous lamellae: 



In this division of the class of Polypi, the Corallum is in general calcareous, and may be 

 either tubular, cyathoid, discoidal, or basal ; but never assumes the form of cylindrical, 

 tubular, horny sprigs, bearing simple bell-shaped cells, for the reception of the contracted 

 tentacula, as we usually find in the sub-class of Hydraria. 



Corallaria present three principal structural modifications, and must therefore be 

 subdivided into three corresponding groups or orders : Zoantharia, Alcyonaria, and 

 Podactinaria. 



Order 1. 

 ZOANTHARIA. 



Zoanthaires (Zoantha), Blainville. Manuel d'Actinologie, p. 308, 1834. 



Zoanthaires {Zoantharia), Milne Edwards. Elem. de Zoologie, p. 1045, 1835; Annot. de Lamarck, 



Anim. sans Verteb., torn, ii, p. 106, 1836. 

 Zoophyta helianthoidea, Johnston ; in Mag. of Zool. and Bot., vol. i, p. 448, 1837 ; Hist, of British 



Zoophytes, p. 207, 1838. 

 Zoantharia, J. E. Gray. Synop. Brit. Mus., 1842. 



Actinaria, Dana. United States Exploring Expedition, Zoophytes, p. 112, 1846. 

 Anthozoa helianthoidea, Johnston. Hist, of Brit. Zooph., 2d ed., vol. i, p. 181, 1847. 



Polypi with conical, tubular, simple or arborescent, but not bipinnate, tentacula, and 

 with numerous perigastric membranaceous laminae, containing the reproductive organs. 



Zoantharia are in general coralligenous, and almost all the known fossil Polypidoms 

 belong to this natural group of Zoophytes. 



These Corals are very seldom essentially composed of epidermic tissues, nor do they 

 scarcely ever constitute basal stems, as is usually the case in Alcyonaria. They are almost 

 always formed of calcified dermic sclerenchyma, and inclose, more or less completely, the 

 inferior portion of the great visceral or gastric cavity of the Polyp. Each individual has in 

 general the form of a deep cup or a tubular sheath, the cavity of which is subdivided into a 

 circle of loculi, by vertical septa affecting a radiate disposition. No trace of any such septa 

 is ever met within Corals belonging to other animals of the same class, and although these 

 parts are sometimes rudimentary in Zoantharia, the starlike appearance of the calice pro- 



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