254 BRITISH SEA-WEEDS. 



set with simple, slender, spine-like, awl-shaped branchlets ; 

 cells of the membrane rectangular. Fructification con- 

 tained in the cells. 



This is a very generally distributed and variable 

 plant. It is less robust and more branched than E. 

 compressa, and all the divisions of its fronds are acute 

 at the tip, while those of the latter species are obtuse. 

 No less than three forms, besides the type, have been 

 figured and described by authors as distinct species ; 

 but the result of recent research has been to degrade 

 them to the rank of varieties, and as such I insert 

 them. They are — 



E. clathrata var. Linkiana. Link's Entero- 

 morpha, 



Described by Dr. Greville, and figured by Dr. Harvey 

 (Phyc. Brit. tab. 344), from a single specimen col- 

 lected by Captain Carmichael, and preserved in the 

 Dublin University Herbarium. 



E. clathrata var. erecta. The erect Entero- 

 morpha, 



Which appears to be a luxuriant deep-water form, with 

 longer, more slender, less rigid, and more numerous 

 branches and branchlets than the typical plant (Phyc. 

 Brit. tab. 43). 



E. clathrata var. ramnlosa. The sharp-branched 

 Enteromorpha, 



Which is distinguished by its squarrose habit, curved, 

 entangled branches, and numerous short, horizontally 

 spreading, spine-like branchlets (Phyc. Brit. tab. 245). 



