170 



SEA-SHORE LIFE 



larva witli large rounded head, and lash-like tail. The larva usually 

 breaks through the egg membrane and swims through the water, 

 avoiding the light. Soon, however, it settles down, and becomes 

 fast to the bottom by means of the adhesive slime of its body. Often 

 it becomes fastened by the tail, but occasionally by its head or some 

 other part of the body. The little creature then struggles vainly 

 to free itself for a time, but soon the tail becomes absorbed, the 

 nervous system degenerates and the animal becomes a Gwna, fixed 

 for life to one spot, and in its adult state no one would suppose 

 that it was in reality a vertebrate. 



Molgula mcmhattensis, Fig. 119. This is found under stones, 

 etc., below low tide level from Maine to the Carolinas. The body 



is aboiit one inch in diameter, rounded 

 in outline and usually covered more or 

 less with particles of sand and detritus. 

 In color it is dull olive green. Two 

 long tapering spouts project upward, the 

 uppermost being for the admission, and 

 the lower for the discharge of water 

 which passes through the gills. Alto- 

 gether the creature presents the appear- 

 ance of the Avater bottles made of skin, 

 such as are still used in the Orient, and 

 indeed the name ascidian signifies a 

 little water skin. The eggs are laid 

 a little before daybreak during the sum- 

 mer months, and the larva develop in a 

 few hours into little tadpoles within the egg membrane, and finally 

 change into fixed tunicates without being set free from the egg 

 membrane. 



This species may often be seen in the New York Aquarium, 

 where colonies of volunteer growth attach themselves to the rocky 

 linings of the tanks, and attain full growth in about six weeks. 



The Star-Spangled Jelly, (BotryUns gouldiij. This compound 

 ascidian ranges from New Jersey to Maine, and is very abundant 

 late in summer upon eel grass. It forms smooth, thick, gelatinous 

 expansions of various colors, such as gray-green, dull yellow, brown, 

 purple, or spotted with white. The whole surface appears as if 



Fi,^. ii<); MOLGULA MANHAT- 

 TENSIS. Woods Holl, Mass. 



