Shell Life 



Gaping File-shell 



foot of the animal is fincrer-shaped and grooved ; and 

 its lips are furnished with tentacles like those of the 

 mantle. Like the Scallops the File- 

 shells spin a byssus, which may be 

 an easily detachable cord whereby 

 they temporarily attach themselves, or 

 may be an enveloping tissue like that 

 of the Horse Mussel, only in this case 

 it would be plastered over with excre- 

 ment, gravel, shell fragments, and sea- 

 weeds, forming a nest in which are 

 several youngsters or one adult. The 

 native species are four in number. 

 The Elliptical File-shell (X. eUiptica) 

 is a small species confined to the waters of the west 

 coast of Scotland and Shetland. Its shell is oval 

 or elliptical, thin and gloss}^ in spite of the 30 or 

 40 fine ribs with toothed crests which radiate from 

 the prominent beaks. The valves have small tri- 

 ano-ular ears, and are connected by a slight ligament. 

 The body and foot of the animal are pale orange, 

 whilst the tentacles are more pink in hue. It inhabits 

 sandy mud in water from 15 to 85 fathoms deep. 



The Heart File-shell (X. siihauriculata) is smaller 

 than the last, more oblong, more convex, and with 

 only 24 ribs, of which the middle one is the 

 largest. The beaks projecting beyond the 

 hinge are very prominent. The animal agrees 

 in colour with the white shell, and uses its 

 white foot for crawling. It is generally dis- 

 tributed round our coasts where there is a 

 sandy or gravelly bottom at a depth from 18 to 

 fathoms. 



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