THE SEA-SQUIRT, OR ASCIDIAN. 429 



nearly related to the Mussels, and was therefore classed 

 with the Soft-bodied Animals (Mollusca). But since 1866, 

 when the remarkable germ-history of these animals was 

 first understood, there has been no doubt that they are 

 unconnected with the Soft-bodied Animals. On the con- 

 trary, greatly to the surprise of zoologists, the. entire mode 

 of their individual development indicates that they are the 

 nearest allies of the Vertebrates. In their matured con- 

 dition the Ascidians are shapeless lumps, which at first 

 sight certainly do not look like animals. The oblong body, 

 often rough, or covered with uneven knobs, in which no 

 definite outward organs are distinguishable, adheres firmly 

 by one end to sea-weeds, stones, or to the bottom of the 

 ocean. Some species resemble potatoes, others dried plums. 

 Many Sea-squirts form very insignificant incrustations on 

 the surface of stones and plants. Some of the larger kinds 

 are eaten Hke oysters. Fishermen, who know them well, 

 regard them not as animals, but as sea-weeds. They are 

 frequently offered for sale together with other low sea- 

 animals, in the fish-markets of many Italian seaside towns, 

 under the name of Sea-fruit (friUtl di ■mare). There is 

 indeed nothing outwardly indicating an animal. When 

 they are drawn from the sea in a drag-net, all that is 

 noticeable is that they feebly contract their bodies, thus 

 producing a spirting of water from certain parts. Most of 

 the Sea-squirts are very small, only a few lines, or at most 

 a few inches long ; a few species attain the length of a foot 

 or rather more. There are a great many species, which are 

 to be found in all seas. We find no fossil remains of this 

 class of animals, because they have no hard parts capable 

 of petrifaction; but they are certainly of very great an- 



