120 CLASS IT.— ORDER II. 



favoars the presumption that, they are placed as in 

 the preceding genera, at the extremities of the 

 branches. The Corallinas, far from indicating this 

 character, appear on the contrary covered on the 

 surface with polypiferous filaments, which, though 

 scarcely retractile, are yet endowed with a move- 

 ment that can only be attributed to life. 



The Janias resemble the Corallinas in their sub- 

 stance, and particularly in those oval bodies which 

 are looked upon as ovaria, and thus form a perfect 

 analogy between the two groups ; this analogy is 

 most discernible in the Jania coniictilata, which 

 sometimes exhibits all the characters of a true Co- 

 ralline in its lower part, whilst the upper is wholly 

 devoid of them. 



Thus then, as previously observed, may these Po- 

 lypidoms be considered as intermediates between the 

 Corallinas and the Galaxauras, without decidedly be- 

 longing to either the one or the other. 



In the bosom of the sea, the Jania$ are of a green- 

 ish violet ; this colour changes to a rose, or bright red, 

 which becomes pure white by the action of air and light. 



Their height never exceeds four centimetres, but 

 some of them are not more than three millemetres high. 



They are found in all latitudes, and in all depths ; 

 in general parasites on the marine plants, which they 

 sometimes wholly cover with a thick coating. 



GIBBOUS. 



1. Jania gibbosa. Articulations swelled in the 

 central part : height from one to three millemetres. 

 On the Fucus latifolius of the Red Sea. 



