70 CCELENTERATA AND 



is either direct (without metamorphosis) or indirect. The 

 larvae of the free-swimming kind are as follows : 



A. With long flexible ciliated arms. Transparent. 



Brachiolaria. 



B. With long inflexible ciliated arms. Each arm with 

 calcareous axis Plnteus. 



C. No arms, with rounded prominences, not ciliated, 

 bright red, opaque False pupa. 



D. No arms, barrel-shaped, girt by parallel bands of 

 cilia Pupa. 



E. No arms, with irregular lines or bands of cilia. No 

 eye-spots. 



1. Single convoluted band about mouth. 



Young Brachiolaria. 



2. Double convoluted band non -continuous. 



Auricularia. 



A. Brachiolaria. 



The Brachiolaria is the young of the star-fish, Asterias. 

 It has a bilateral arrangement of lon«* flexible arms. 

 Transparent, slightly pigmented arms. With large open 

 mouth, oesophagus and intestine. Elongated water-tube 

 on each side of stomach. Dorsal pore. Young star-fish 

 appears on left water-tube at or near region of stomach. 



B. Pluteus. 



1. Pluteus with two arms, very long . Ophiopholis. 



2. Pluteus with anal arms Arbacia. 



3. Pluteus with epaulettes . . Strongylocentrotus. 



4. Pluteus without epaulettes . . Echinarachnius. 

 The pluteus is the larval condition of the Ophiuroidea 



and Echinoidea. It is distinguished by the possession of 

 calcareous axes in the arms. 



