587 



Class TUNIC ATA. 



Acephalous Mollusks with a soft, organized, coriaceous 

 or gelatinous shell or test provided with a branchial and 

 an anal orifice. Mantle forming an interior coat. Gills 

 attached wholly or partly to the internal surface of the 

 mantle. Mouth without lahial tentacles, placed below the 

 gills. Animals single or aggregate, fixed or free, her- 

 maphrodite, undergoing a metamorphosis in their young- 

 state. 



The Tunicaries are entirely marine, and are very nume- 

 rous in all parts of the world ; adhering to rocks and sea- 

 weed, their strange, bag-shaped, leathery bodies may be 

 seen along the strand at low-water, ejecting, when touched, 

 the sea-water to some distance; and on the ocean their 

 lengthened sinuous chains, or pellucid phosphorescent 

 tubes cannot fail to arrest the eye of the voyager. The 

 compound forms exhibit, in the varied arrangement of the 

 individuals composing the general mass, a number of ele- 

 gant stars and flowers of curious aud complicated design. 

 Towards the northern shores they are sombre in their 

 colours, but in the sunny regions of the south their hues 

 assume the brightest dyes, and vie with those of the coral- 

 lines and Actinice that people the bed of the ocean. It was 

 in the Ascidian Tunicaries that MM. Audouin and Milne- 

 Edwards first discovered the metamorphoses of the Mollusca, 



