70 THE AQUARIAN NATURALIST. 



ments in general are remarkably slow, and its appear- 

 ance anything bnt indicative of energy or activity. 



Nevertheless, fixed and apathetic as these creatures 

 seem, helpless and inactive as they might be sup- 

 posed, few denizens of the aquarium will be found 

 more voracious, or better able to satisfy their craving 

 appetites. Who would believe that that transparent 

 bag, hanging listlessly and lazily in the water as 



"The fat weed that roots itself at ease 

 On Lethe's wharf," 



is a destroyer more redoubtable than even the fabled 

 Hydra after which it takes its name? Who would 

 dream, that those long silken threads which wave so 

 prettily around its mouth were instruments of death 

 more terrible than all Medusa's snakes? The food 

 of the Hydra is by no means limited, as we might 

 naturally conjecture, to vegetable particles or micro- 

 scopic infusoria ; on the contrary, creatures the most 

 active of their kind not unfrequently fall victims to 

 its rapacity, and its powers of destruction seem only 

 to be restricted by the smallness of its dimensions. 

 Observe the specimen before us, with its tentacula all 

 expanded hundreds of active little beings swimming 

 round it tiny shrimps of various forms disporting 

 themselves in the water, any one of which appears ten 

 times a match for such a sluggish foe. The Hydra 

 seems unconscious of their presence, and hardly deigns 

 to sweep the water with its lazy arms to seek its break- 

 fast ; but now a passing shrimp has hit against one 

 of the outstretched tentacles, and instantly arrested 

 in its course, succumbs before the magic touch ; the 



