THE LANCE LETS 2937 



the seashore or sea bottom. If an individual be dropped from the hand on to a 

 mound of wet sand, which has just been dredged out of the water, it will burrow 

 its way to the lowest depths of the sand hillock in the twinkling of an eye. Its 

 usual modus vivendi is to bury the whole of its body in the sand, leaving only the 

 mouth with the expanded buccal cirri [tentacles] protruding. When obtained in 

 this position in a glass jar, a constant inflowing current of water, in which food 

 particles are involved, can be observed in the neighborhood of the upstanding 

 mouths. The food consists almost entirely of microscopic plants (diatoms, desmids, 

 etc. ) and vegetable debris. . . . Occasionally it emerges from its favorite posi- 

 tion in the sand, and after swimming about for some time it will sink to the bottom, 

 and there recline for a longer or shorter period upon its side on the surface of the 

 sand. When resting on the sand, it is unable to maintain its equilibrium in the 

 same position as an ordinary fish would do, but invariably topples over on its side, 

 indifferently, the right or left; " this inability to maintain its balance being due 

 to the absence of certain structures of the internal ear, to which this function is as- 

 signed in fishes. According to another observer, lancelets occasionally attach them- 

 selves to another by their mouths in a chain-like manner, as represented in our 

 illustration. That lancelets indicate an extremely archaic type, and also that they 

 are more nearly allied to the Vertebrates than to the Invertebrates, may be consid- 

 ered certain; although there is still a difference of opinion whether they should be 

 looked upon as simple or degraded forms. 



