62 CLASS I.— ORDER I. 



FEATHERY. 



12. Crisia plumosa. Stem very branching, up- 

 right and dichotomous ; cells unilateral, alternate, and 

 terminated at the summit by a point. 



European seas. 



MENIPEA. 



Plant-like Polypidom; branching and articu- 

 lated ; cells having their opening on the same side, 

 and many united together in concatenated masses. 



The general appearance of the Menipeas, and the 

 singular form of their cells, give them a distinct and 

 peculiar character. Their branches bend in the form of 

 plumes, and instead of straightening, curve still more 

 when put into water. Their cells, more or less nume- 

 rous, are placed in masses of a triangular form, and 

 linked one to the other, having their opening always 

 on the same side and in parallel lines ; there are ge- 

 nerally three placed on the larger part of the wedge, 

 two on the second line, and then a single one termina- 

 ting this reversed pyramid ; sometimes there are only 

 two rows of cells, and even a single one placed at 

 each articulation. The Menipeas bifurcate at each 

 articulated mass. 



Their substance appears more calcareous than 

 membranous or horny ; they are very friable, and 

 preserved with diflficulty. 



Their colour is a yellowish white, bordering on 

 grey. 



