26 ’ 
A more abundant species is Pholas truneata Say. It 
bores in stiff mud, between tides, making a perpendicular 
round hole, sometimes a foot 
)\ \ _or more in depth. Fig. 29. 
}}\ Zirphea crispata Linn. is 
2 often found in soft wood. Its 
tunnels are very small at the 
opening, larger within. A 
whole colony sometimes lives 
in a single small piece of float- 
Fig. 30. Zirphza crispata. 
ing wood. 
The Teredo nayalis Linn. or Ship 
Worm, is the pest of sea-faring 
men. It riddles wharfs or submarine 
woodwork of any kind, with its long 
tunnels, lined with a white chalky 
layer. The body of the Teredo is long 
and worm-like; the shell is small, and 
situated at the extreme end of the 
burrow. The shells are white and 
fragile, and have a certain resemblance 
to the Pholas. 
Teredo, like other boring mollusks, 
does not eat the wood from its ex- 
eavations, but obtains food from the sea 
water which it draws in through the 
perforation with which the burrow 
Fig. 31. Texedo navalis. 
begins. 
