344 NATURAL HISTORY. 
tached, at regular distances, a multitude of shorter and 
much more slender fibres, which are coiled up in spirals 
when the main filament contracts, and gradually spread 
out as it lengthens. These are very similar to the small 
hooked threads attached at intervals along a fishing-line.” 
Questions. —What is said of the symmetry of the Radiates? What 
of the structure of the Actiniz ? What is the office of the chambers 
around the stomach? What are the type-families among the Radi- 
ates? What is said of the locomotion of the Radiates? What of 
their resemblance to vegetables? What of their senses and nervous 
system? What are their cilia? Describe their mode of action. 
What purposes do they effect? What are the three classes of Radi- 
ates? What is the structure of the Starfish? In what way does it 
walk? How does it take its prey? What is said of the motion of 
its arms? What is said of the order Stellerida? What is the struc- 
ture of the Echinus? How does it walk? What is the plan of its 
shell, and how does it grow? Where are the Echini found, and 
what are their habits? What is said of their masticating apparatus ? 
What is the mode of their development? What is said of two aber- 
rant orders of Echinoderms? What animals constitute the second 
class of Radiates? What are their peculiarities? What is said of 
the Medusze ? How are they like the Actiniz, and how unlike them ? 
Where are the Acalephs generally seen? What is said of the phos- 
phorescence of the sea? What is said of the Beroe? 
CHAPTER XXXV. 
RADIATES — continued. 
598. We come now to a class of Radiates including 
animals which are, with some few exceptions, entirely 
different from those of the classes already considered in 
relation to locomotion. Most of the Echinoderms craw]; 
some of them, and all the Acalephs, swim; but the Pol- 
ypes are, for the most part, like plants, fixed to the spot 
where they begin life. The older botanists described 
these animals as plants, and arranged them with sea- 
weeds and mosses. The Sea Anemone was considered a 
flower, and the analogous beings found in coral and mad- 
