How Animals Work. 



outer edges of the mantle, which broadens out like a 

 wing, and is bordered with a delicate fringe of the 

 finest hair, or cilia. As the little Trochus moves slowly 

 along through the water, the rippling, wave-like move- 

 ments of the fringe of cilia cause a wonderful play of 

 iridescent colours round the head of the Mollusc, mak- 

 ing it look as if dressed in " a rainbow frill." In fact, 

 one cannot help feeling that it is the original of Tenny- 

 son's lines. The shell has a nearly flat broad base, 

 and tapers abruptly, so that the general shape is some- 

 thing like a squat peg-top ; but both shape and colour 

 vary a good deal in different species, some being much 

 taller than others and quite smooth, covered with little 

 knobs, or with a tracery of ridged lines running round 

 and round from the base of the shell to the apex. 



A living Ormer, or Ear-shell, does not present at all 

 an interesting or striking appearance, and one would 

 never imagine that beneath that rough, grayish-brown 

 exterior lay hidden the most gorgeous tints, vivid as a 

 tropical sunset, softly opalescent the whole gamut of 

 an artist's palette. When, however, the shell is empty 

 and its tenant dead, it is seen to be lined with 

 the most beautiful mother-of-pearl, while the removal 

 of the outer rough layer and subsequent polishing of 

 the upper surface will reveal fresh wonders of colora- 

 tion. 



The Cowries of the Tropic seas offer a contrast in 

 shell structure, for, instead of the dull, rough exterior 

 of the Ormer, their surfaces are always more or less 

 brightly coloured and highly polished, the wonderful 

 smooth glistening surface being produced by the mantle, 

 which folds back over the outer surface of the shell 



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