LESSON 30.] 



NUTRITION IN POLYPI. 



103 



FIG. 177. 



LESSOR XXX. 



ORGANS OF NUTRITION IN POLYPI. 



512. We have now to consider the structure of an extremely in- 

 teresting class of animals, moderately minute in size, and of won- 

 drous beauty ! 



The Polypi (poly, many ; pes, feet) are so called from their 

 general resemblance to the many armed Cuttle-fishes, and these ob- 

 tained the name of "many feet " from the Greek naturalists. They 

 are almost universal in their distribution ; inhabiting the fresh water 

 pools in great abundance, they form objects of surpassing interest to 

 the naturalist. 



513. But for endless variety of external form, associated with 

 every shade of color, we must seek 



for these charming creatures in the 

 Ocean. 



The limits of this work will 

 not permit an extended notice of 

 these animals ; and in the present 

 connection we are in search of nu- 

 trimental organs, chiefly. 



514. The fresh waters furnish 

 three species of Hydra; H. vul- 

 garis; H. fusca, and H. viridis, 

 or green Hydra. Of these, the H. 

 fusca is less common, and by far 

 the most beautiful (Fig. 177). The 

 tentacles, as the arms are called, 

 are shorter than the body in H. vul- 

 garis, but in this species they are 

 of very great length, and when seen 

 in a glass jar groping about, and 

 searching for prey, present an ob- 

 ject of incredible magnificence ! 



515. The Hydrse are carnivo- 

 rous ; feeding upon the minute ani- 

 mals (especially Crustaceans) which 

 are found abundantly in the same 

 pools. The instant a tentacle 



touches an animal, although its body may be rotected by a shell, it 



Hydra fusca. 



