,'320 



Natural History of British Zoophytes. 



laria antennina grows on rocks, Campanularia genicnlata delights to 

 cover the broad frond of the tangle with a fairy forest peopled with 

 its myriads'of busy polypes, while the Sertularia pumila rather loves 

 the more common and coarser wracks. The choice may in part be 

 dependent on their habits, for such as are destined to live in shallow 

 water, or on a shore exposed by the reflux of every tide, are in gene- 

 ral vegetable parasites ; while the species which spring up in the deep 

 seas must select between rocks, corallines or shells, the depths at 

 which they are found being too great for the vegetation of sea-weed.* 

 The polypidoms are confervoid and more or less divided, the ra- 

 mifications being disposed in a variety of elegant plant-like forms. 

 The stem and branches are alike in texture, slender, horny, fistular, 



* Lamouroux says, — " We find some polypidoms placed always on the south- 

 ern slopes of rocks and never on that towards the east, west, or north. Others, 

 on the contrary, grow only on these exposures, and never on the south. Some- 

 times their position is varied according to latitude, and the shores inclined to- 

 wards the south, in temperate or cold countries, produce the same species as 

 the northern exposures in equatorial regions : in general their branches appear 

 directed towards the main sea." — Corall. Flex. Introd. p. L. 



