CLASSIFICATION OF R ADI AT A. 443 



Nearly all of them possess both a stinging power and the pro- 

 perty of phosphorescence. 



III. POLYPIFERA, or polype-bearing animals. This includes 

 the beings commonly termed Zoophytes, or Animal-Plants, on 

 account of the resemblance in their mode of growth to that of 

 Vegetables. Although the various forms of Corals, Madrepores, 

 &c., which belong to this group, are themselves of an irregular 

 form, the individual polypes (as already remarked 991) possess 

 the regular radiated conformation. And, as many species of 

 polypes live separately, it is obvious that we should look to 

 these, and not to the structures which they form, for the cha- 

 racter of the Class; and to their varieties, for the characters of its 

 subdivisions. 



998. In the higher species of all these groups, which possess 

 sufficient firmness and definiteness of structure to allow of a ner- 

 vous system being detected, its form is found to correspond with 

 the characteristic disposition of other organs. It consists of a 

 circular filament surrounding the mouth, on which are a number 

 of ganglia (or distinct centres of nervous action) usually equal to 

 that of the segments of the body, and disposed at regular inter- 

 vals. From these, diverging filaments are sent off, which are 

 distributed to the various organs with great regularity. From 

 this arrangement of the nervous system, the term Cyclo-neura 

 (circular-nerved) has been applied to this division of the Animal 

 kingdom, and is sufnciently characteristic of it. 



999. Besides these classes, there are two others, in which 

 neither nervous system nor radiated structure can be detected - y 

 but which must, for the present at least, be referred to the same 

 group, although not possessing the radiated structure. 



IV. PORIFERA, or animals whose surface is covered with 

 pores. This group comprehends the Sponge tribe, and may be 

 considered as intermediate between Polypifera and Plants. 



V. POLYGASTRICA, or many-stomached animals. This name 

 has been given to the lower of the two groups into which, since 

 the researches of Ehrenberg, the Infusorial Animalcules have 

 been divided. It is believed by that Naturalist, that they pos- 

 sess a large mmvber of separate digestive cavities, with distinct 



