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FIG. 50. 



A, Two living specimens of H. viridis attached to a bit of weed. 

 The larger specimen is fully expanded, and shows the elongated body 

 ending distally in the hypostome (hyp], surrounded by tentacles (/), and 

 three buds (?>ifl, bd' 2 , bd' A } in different stages of development : a small 

 water-flea (a) has been captured by one tentacle. The smaller specimen 

 (to the right and above) is in a state of complete retraction, the tentacles 

 (0 appearing like papillae. 



B, H. fiesca, showing the mouth (mth] at the end of the hypostome 

 (hyp], the circlet of tentacles (/), two spermaries (spy), and an ovary 

 (ovy}. 



C, a Hydra creeping on a flat surface by looping movements, 



D, a specimen crawling on its tentacles, 

 (C and D after W. Marshall.) 



