8 



MARINE AND FISHERIES 



5 GEORGE v., A. 1915 



Here again, as with Actinotrocha, the free-swimming larva gives place to the shore- 

 dwelling adult. 



The starfish is known as a serious enemy of oysters, but there can be no ques- 

 tion that the larvae are a valuable commodity of the neritic plankton. 



Fig. 2. Brachiolaria larva identified with that of the common starfish {Asterias 

 vulgaris); represented in the attitude of swimming, in the direction indicated by the 

 arrow. The outline of the developing starfish occupies the hinder end of the larval 

 body; the position of the mouth is seen behind the tentacle (one of a pair, the other not 

 shown) which follows the three adhesive arms. 



The fixed Tunicata or sea-squirts, to which reference has been made above, 

 produce tailed larvae known as Ascidian tadpoles. At the front end of the body 

 these tadpoles are provided with three adhesive processes which in some cases 

 are borne upon relatively long stalks. Of these processes one is median and 



