viii BRITISH FOSSIL CORALS. 



CLASSIFICATION OF POLYPI. 



Sub-kingdom ZOOPHYTA; Section RADIATA. 



Class 

 POLYPI. 



Animals of the sub-kingdom of Zoophyta, and of the section of Radiata, 1 organized 

 for a sedentary mode of life, having no locomotive organs, and being provided with a circle of 

 retractile tentaculse around the mouth, and a central gastric cavity, not communicating with 

 an anus, and containing the reproductive organs when these exist ; in general fissiparous, 

 or multiplying by buds as well as by ovules. 



The systems adopted by Cuvier, Lamarck, Lamouroux, and their contemporaries, for the 

 subdivision of the class of Polypi, were founded on external characters of very little value, 

 and were quite artificial. In a Memoir, published about twenty years ago, 3 a first attempt 

 was made to establish this classification on anatomical facts, and the Zoophytes presenting 

 the above-mentioned structure were distributed in two groups, characterised by the pre- 

 sence or the absence of internal ovaria, and a membranaceous tube leading from the mouth 

 to the great gastric cavity. Subsequent observations have confirmed these views, and 

 Mr. Dana, whose recent work 3 is one of the most valuable contributions which America has 

 yet made to Natural History, divides in a similar manner the class of Polypi into two 

 secondary groups. We shall continue adopting this classification here ; but the name of 

 Actiuoidea, which Mr. Dana applies to the first of the two sub-classes thus established, 

 having been previously employed by other zoologists in a much narrower acceptation, we 

 have thought it advisable not to make use of it here, and we propose substituting for it that 

 of Corallaria. The second group comprises the Sertulariati Polypi (Milne Edw.), and may 

 lie designated by the name of Ili/draria. 



1 The sub-kingdom of Zoophytes may be divided into two natural groups : the one comprising all the 

 i rue Radiate animals (Echinoderma, Aealepha:, and Polypi) ; the other containing the spheroidal or amor- 

 phous Zoophytes (such as Spongidse and certain Infusoria). The first may retain the name of Radiata ; 

 Ihr second has been designated by that of Sarcodaria (Milne Edwards, Cours elementaire de Zoologie). 



2 Recherches sur les Animaux sans Vertebrcs, faites aux ties Chausay, par MM. Audouin et Milne 

 Kdwards (Annales des Sciences Naturelles, premiere serie, t. xv, p. 18, Septembre, 1828). 



3 United States Exploring Expedition ; Zoophytes. Philadelphia, 1846. 



