THE EUROPEAN SEAS. 159 



There is a large compound Ascidian, easily to be 

 mistaken for a Zoophyte, so abundant at times that 

 the fishermen's nets become choked with it, and 

 which, when thrown upon the beach, is amorphous 

 and repulsive enough. When in the water it is 

 seen to be a most remarkable form of aggregate 

 life, consisting of a hollow cylinder closed at one 

 end, and made up of hundreds of distinct animals 

 set side by side : this is the Pyrosoma — the Fire- 

 body. 



Though common, it has, perhaps, more frequently 

 attracted attention at night than day, for, of all the 

 numerous phosphorescent animals of Lusitanian 

 seas, this is, perhaps, the most so. In particular 

 states of the atmosphere, these animals light up the 

 water by their intense fire-like glow. There are 

 several species, but all belong to the warm regions 

 of the Atlantic, and have their northern limits in 

 the Lusitanian zone. 



Many more products of the sea are eaten in 

 son them regions than with us. Ascidiamicrocosmus 

 is a favourite on the coasts of the gulf of Genoa, 

 and A. rustica on those of Greece and the Adriatic. 



The Mediterranean Pteropods beloDg mainly to 

 the genera Hyalcea, Cleodora, and Creseis, forms 

 wholly unknown to our own fauna except as waifs. 

 Vast shoals of these animals frequent the deeper 

 parts of that sea, leaving their remains strewed over 

 its bed, between depths of 100 and 200 fathoms; 

 they are short-lived creatures, and have their season, 



