PHOLADID^. 



51 



Family I. Pholadid^. 



bneii gaping at botli ends, tliln, white, 

 roughened \[^q ^i rasp, without hinge or liga- 

 ment ; strengthened by accessory valves, 

 n Animal club-shaped; foot short, trun- 



' ' cate ; mantle open only for the protrii- 



sion of the foot ; siphons large and 

 long, united nearly to their tips, their 

 orifices fringed. Borers into various 

 substances. 



Teredo (Adanson). SMi^-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. 



XyJophaga (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. 



Pholas (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 



60 



