HABITS AND DISTRIBUTION. II 



water which is drawn into the mouth by the powerful 

 ciliary action of the cells lining the roof of the mouth and 

 the wall of the pharynx. 



Speaking generally, Amphioxus is an inhabitant of 

 shallow water; it is essentially a littoral form, and is apt 

 to occur in the neighbourhood of any sandy shore. Its 

 occurrence, however, is often curiously local, as shown by 

 its behaviour at Messina. In the vicinity of Messina 

 there are a couple of rather extensive salt-water pools, at 

 some points of considerable depth, which, in the course of 

 ages, have apparently been shut off from the adjacent sea 

 by the formation of sandbanks. In the more northerly of 

 these small lakes, lying almost at the extreme north- 

 eastern point of Sicily, Amphioxus occurs in astonishing 

 abundance ; while in the more southerly lake, which is 

 connected with the former by a narrow artificial canal, it 

 is entirely absent. Both of these lakes communicate 

 by narrow outlets with the Straits of Messina, where, 

 however, Amphioxus is somewhat rarely met with. In 

 the Gulf of Naples it is extremely abundant ; while in 

 Plymouth Sound, in the English Channel, it is compara- 

 tively rare. On the coast of France it is said to grow to 

 an unusually large size. It has been taken in greater or 

 less numbers from many other localities in Europe, on 

 the Atlantic and Pacific shores of North and South 

 America, and from the shores of Australia, Japan, and 

 Ceylon. Its geographical distribution may therefore be 

 said to be pre-eminently world-wide, and, in fact, it is 

 liable to turn up on any shore in the temperate and 

 tropical regions. And yet with all this world-wide distri- 

 bution there is only a single genus, with some eight 

 species,* the different species being remarkably alike, 

 differing slightly in the height of the dorsal fin and in 



