PHOLADID^S, 



51 



FAMILY I. PHOLADID^. 



Shell gaping at both ends, thin, white, 

 roughened lik e a ra sp, without hinge or liga- 

 ment ; strengthened by accessory valves. 

 Animal club-shaped; foot short, trun- 

 cate ; mantle open only for the protru- 

 sion of the foot ; siphons large and 

 long, united nearly to their tips, their 

 orifices fringed. Borers into various 

 substances. 



Teredo (Adanson). Ship-worm. Shell 

 of two curved equal valves, gaping at 

 both ends. Animal worm-like, not co- 

 vered by the shell ; mantle tubular ; 

 siphons long, forked at the tips. Bores 

 into wood, which it lines with a shelly 

 tube. 



T. Norvegica. Fig. 60 ; n. s. 



navalis. 



megotara. 



bipennata. 



Xylophaga (Turton). Shell as in 

 Teredo, but gaping only in front. Ani- 

 mal covered by the shell ; makes a ca- 

 vity in wood, which is not lined with 

 shell. 



X. dorsalis. Fig. 61 ; n. s. 



PJiolas (Linn.). Piddock. Shell oval 

 or oblong, equal- valved, unequal-sided, 

 gaping, chiefly in front ; exterior beset 

 with transverse ridges, and longitudi- 

 nal furrows ; beaks covered with cal- 

 losities ; accessory pieces to the valves. 

 Animal thick ; siphons very long, united except at 

 E 2 



