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HANDBOOK OF INVERTEBRATE ZOOLOGY. 



a. The structure of the larva. 



At first sight there seems to be little likeness between 

 the starfish larva (Figs. 78 and 79), and the pluteus of 

 a sea-urchin, but more careful examination shows that 



FIG. 78. 



FIG. 78. Bipinnarian larva of starfish, as seen in ventral view. 

 {Drawn from nature by E. B. Wilson. ) 



a. Anterior end. a'. Pre-oral arras, b. Posterior end. 1. Pre-oral 

 ciliated ridge. 2. Post-oral ciliated ridge. 3. Anterior median ventral 

 lobe. 4- Anterior median dorsal lobe. c. Post-oral arms. i. Intestine. 

 m. Mouth, n. Lateral arm. o. Anus. oe. (Esophagus, q, q.' Dorsal 

 lateral arms. s. Stomach, ww'. Water tubes, am. Flattened poste- 

 rior end of left water tube. 



