68 CLASS I.-»-ORDER II. 



thoy adhere by their lower part ; in fine, there are some 

 in which these lines cease to project forward, and are 

 attached to the stem by the back part of the cells. 

 Therefore, notwithstanding the apparent difference be- 

 tween the Amathia hndigera, and the A. spiralis, it is im- 

 possible to place them in separate genera, on account 

 of the intermediate species which gradually link toge- 

 ther beings at first sight exceedingly dissimilar. 



No distinct character can be formed from the dis- 

 tance which separates these cellular groups from 

 each other ; in the Amathia leudigenty so common in 

 our seas, we find individuals in which all the groups 

 of cells touch, and others in which those same groups 

 are distant two or three millimetres from each other. 

 It is in the number and the form of the cells of each 

 group, in their situation, ramification, &c., that we 

 find the means of distinguishing the species. 



The Amathias are of a horny substance, very 

 slightly cretaceous. 



Their colour is a brown fawn, more or less deep. 



They vary in height from one to fifteen centimetres. 



They are frequently found parasites on the Tha- 

 lassiophytes ; sometimes they adhere to rocks or other 

 hard marine productions by a fibrous base. 



They appear more common in the equatorial and 

 temperate seas, than in the cold or icy regions of 

 either pole. 



LENDIGEROUS. 



1. Amathia leudigera. Branching and filiform ; 

 cells with an even border; groups at unequal dis- 

 tances, sometimes very wide apart. 



European seas. 



