206 LECTURE Xfl. 



Tubularia. The marine genus called Flustfa at 

 first view so much resembles afucus or sea- weed, 

 that it has been commonly described as such be- 

 fore the time of Mr. Ellis 5 who determined its 

 real nature. It consists of flat, branched, leaf-like 

 processes, each composed of very numerous cells, 

 of a slightly horny or tough substance, open at the 

 top, and affording a passage to the animal part or 

 polype-head, which, in the recent zoophyte, pro- 

 trudes through each cell ; and the regular manner 

 in which the cells are disposed, gives the leaf or 

 plant-like appearance to the whole. The most 

 common species is the Fl. foliacea, or broad-leaved 

 Flustra, common on our own coasts. 



I shall now proceed to give an example or two 

 of the principal genera of the hard or strong 

 Zoophytes, more generally called Corals. Of these 

 some are furnished with a kind of horny stem or 

 central part, covered over throughout all the rami- 

 fications by a soft bark of a calcarious nature, and 

 in which the animal or polype-like fabric is placed, 

 while in other species the central part or stem is 

 of a stony hardness, and is covered, in a similar 

 manner, by a softer bark containing the anima-l 

 part. The most remarkable genus of the hard 



