RADIATA. 615 



4th Tribe. 

 Axis stony, covered with stellular discs, to which the 

 fleshy substance bearing the polypi is confined. This in- 

 cludes the extensive group included by Linnaeus under 

 his genus Madrepora, which Lamark has subdivided into 

 eighteen genera. The fleshy matter appears to be thin and 

 deciduous, like the Antipathes, easily separating from the 

 stellular discs. The nature of the connection of the fleshy 

 with the stony matter, its form, and the characters of the 

 polypi, have not been distinctly explained. 



Order II. 



Polypi not connected with a fleshy covering, and ha- 

 ving a greater number of tentacula than eight. 



In this order, the tentacula appear to be irregular in 

 number, even on individuals of the same species. The sto- 

 Jnach seems to be a simple bag destitute of intestines, and 

 the ovaria to be external. 



1st Tribe. 



Coral^ with the polypi in cells which are closed at the bot- 

 tom. Each polypus is, in this manner, separated from its 

 neighbour, and lodged in its own cell. This tribe is capable 

 of distribution into groups ; but their characters of distinc- 

 tion are far from being precise. Lamakk has formed them 

 into two divisions, Polypiers a reseau, and Polypiers Jbror- 

 mines. There is not any one character common to all the ge- 

 nera of the first group, except the porosity of the coral; and 

 this character, which is stated as wanting in the second, 

 may be readily observed in several species of Millepora, 

 for example, which he quotes. 



A. Cells imbedded in a stony coral. Here the cells may 

 be considered as excavated out of the surface of the coral, 

 and are usually arranged perpendicular to the axis. The 

 orifices are simple and minute. This group is represented 



