269 



TELLINTD.E. 



THE TELLEN TRIBE. 



A LABGE family of bivalves, often remarkable for ele- 

 gance of form, delicacy of sculpture, and beauty of colour. 

 Some of our most vividly painted British shells are mem- 

 bers of this tribe. The majority of species are thin, fra- 

 gile, and compressed. Whilst they present a general 

 resemblance of external form, although with many modifi- 

 cations of outline, the internal structure, so far as the 

 hinge is concerned, is very different in different genera. 

 The small value of the hinge-characters for indicating mu- 

 tual affinities is, indeed, strikingly shewn in this group ; 

 as examples we may cite Psammohia and Tell'ma^ and con- 

 trast them with Byndosmya and Scrohicularia. 



The animals, however, of all the genera of Tellinida 

 are strikingly similar. They have all very slender, sepa- 

 rate, diverging siphons, often very long, the orifices of 

 which are either quite plain or slightly fimbriated. The 

 margins of their mantles are widely open, and usually 

 furnished with fine short filaments. The foot is broad, 

 geniculated, and linguiform. Although their shells are 

 often painted with glowing hues, the animals are almost 

 always white or colourless. The Tellens are mostly 

 inhabitants of the littoral and laminarian zones, but many 

 species have great ranges in depth, and some are among 

 the inhabitants of the deepest sea-beds yet explored. 



Through Psammohia^ they are evidently related to the 



