90 ZOOLOGY. 



One of the most remarkable features of this class consists 

 in the metamorphosis which the embryo undergoes. The 

 following eloquent description of the metamorphosis of 

 the brittle star is by Mr. Gosse : 



" The first condition of every echinoderm is the same 

 an egg-like body, covered with cilia, resembling an in- 

 fusorium. Changes take place, and we presently see 

 another form assumed, which varies in some degree in 

 the different families. We lately had the pleasure of 

 finding in our dip-net several little larvae of a brittle 

 star, the first that had ever been seen in our seas ; and 

 one of these we will select for description. 



" A painter's long easel affords the only object with 

 which to compare the little creature ; for it consists of 

 four long slender calcareous rods, arranged two in front 

 and two behind, with connecting pieces going across in a 

 peculiar manner, and meeting at the top in a slender 

 head. 



" On this shelly, fragile, and most delicate framework, 

 as on a skeleton, are placed the soft parts of the animal, 

 a clear gelatinous flesh, forming a sort of semi-oval tunic 

 around it, from the summit to the middle, but thence 

 downwards the rods individually are merely encased in 

 the flesh without mutual connection. The interior of the 

 body displays a large cavity, into which a sort of mouth 

 ever and anon admits a gulp of water. Delicate cilia 

 cover the whole integument, and are particularly large 

 and strong on the flesh of the projecting rods. 



" The appearance of this most singular animal is very 

 beautiful, its colour pellucid white, except the summit of 

 the apical knob, and the extremities of the greater rods, 

 which are rose colour. It swims in an upright position, 

 with a calm and deliberate progression. The specimens 

 which we have seen were not more than one-fortieth of 

 an inch in length. 



" From this form the brittle star is developed, but in a 

 manner unparalleled in any other class of animals. The 

 exterior figure is not gradually changed, but the star is 



