Zoophytes with Pinnated Tentacles. 441 



Order II. SPONGICOL.E or IIYALOPIIYTA. 



Subaym metrical, living sunken by the base into a sponge, 

 strengthened by silicious spicula, and supported by a central axis 

 formed of numerous twisted, elongated silicious fibres. 



The axis is formed of many twisted fibres, its lower end 

 tapering, and parasitically imbedded in a fixed sponge, and thus 

 kept in an erect position. 



The animal matter or bark is strengthened by silicious spi- 

 cula, similar to, but shorter and thinner than the fibres of the 

 axis. The fibres are formed of numerous thin concentric layers. 



Valenciennes and other French naturalists, overlooking the 

 structure of the spicula in the bark, have regarded the latter as a 

 parasitic kind of Alcyonarium growing on some unknown sub- 

 stance, — an idea that requires the belief in the existence of two 

 peculiar bodies which are always found together and are unknown 

 in any other state, instead of regarding them as parts of the 

 same animal growth ; this is proved to be the case not only by 

 their being always found in union, but by the fact that the axis, 

 which is supposed to be the supporting part, is of the same 

 texture as the spines found in the bark, the one passing gradu- 

 ally into the other ; and I have no doubt that, in the living state, 

 the fibres of the axis are as much surrounded by flesh as the 

 spicula in the bark itself. 



Fam. 1. Kyaloneinidae. 

 Hyalonema. 



Order III. RUPICOL.E. 



Coral tree-like or expanded, fixed by an expanded base, sup- 

 ported by more or less abundant fusiform calcareous spicula, 

 and often supported by a central calcareous or horny tree-like 

 axis with an expanded base. Living attached by the base of 

 the coral and axis to rocks on the sea-shore. 



This order is divided into three suborders. 



Suborder I. Lithophyta. 



Coral arborescent, supported by a continuous or jointed cal- 

 careous axis, which effervesces with muriatic acid. 



t Axis continuous, not jointed. 

 Fam. 1. Coralliadse. 



Axis inarticulate, solid, calcareous. Bark granular, with 

 irregular-shaped spicula. 



* Cor allium. Annella. Ellisella. (Junceella and Ctenocella.) 

 tGorgonella. Scirpearia. Umbracella. **Subergorgia. 



