ZOOPHYTA HYUROIDA. 



83 



the common medullary pulp is retained, (Fig. 9, h.) * Besides 

 the cells there are found, at certain seasons, a larger sort of ve- 

 sicles, readily distinguished from the others by their size and 

 the irregularity of their distribution.— The more robust tribes 

 grow erect, and, beuig flexible and elastic, yield readily to the 

 waves and currents ; but some of the very delicate species avoid 

 a shock for which they are unequal by creeping along the surface. 



Fiff. 9. 



The polypidoms, when dried, are for the most part of a yel- 

 lowish or horn colour. " When they are immersed in water, 

 they recover the same form they appeared in when fresh in the 

 sea ; and soon become filled with the liquid. This gives them 

 a semitransparent amber colour, and makes them very elastic.""!* 

 Their material appears to be analogous to horn or condensed 



• Lister, in Phil. Trans. 1834, p. 371. 

 t Ellis, English Corallines, p. 3. 



