46 HYDROZOA — MEDUSIPAROUS EEPRODUCTION. 



delicate white tufts or tassels, every one of which, 

 examined closel}^ is found to be a hydra, scarcely 

 different in its form or habits from that we have de- 

 scribed in a preceding page. 



This marine hydra has received the name of 

 Hydra tula: it quite equals in voracity its fresh- 

 Avater namesake, is equally formidable in its arma- 

 ture of lasso-threads, and is ordinarily multiplied in 

 the same manner by buds or gemmae that sprout 

 from its surface : at certain seasons, however, the body 

 of the Hydra tuba becomes considerably elongated, 

 and divided by constrictions into numerous seg- 

 ments, resembling a pile of saucers placed one 

 within the other. Shortly, from the margin of each 

 saucer, tentacles are seen to sprout, not resembling 

 those of the hydra, but those of the medusse, and 



FlG. 30.— FIGURE OF TUHEIS AND ITS YOUXG. 



after a little while these saucers, detaching them- 

 selves successively from the top of the pile, swim 

 awav completely formed and active Acalephee 

 (Fig. 30) 



The Camjmlanarian Zooj^liytes (Fig. 22), as we 

 have exj^laihed, produce their young in elegant 

 transparent vases, which sprout from the bases of 

 their Polype-bearing branchlets, yet when these 

 vases open they send forth, not ciliated embryos, as 

 is the case with the Sertularian Polypes (Fig. 21j^ but 



