70 (XELENTERATA 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. 



(7. 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 long 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. 



