CONCHIFERA, 507 
ito the siphonal tube; siphons very long, united nearly to the 
end, attached at the bifurcation and furnished with 2 shelly 
pallets or styles ; orifices fringed. 
T. Navalis is ordinarily a foot long, sometimes 24 feet; it 
destroys soft wood rapidly, and teak and oak do not escape; it 
—— 
eer yD yap) ) Vey) ) 
ny) BELLU 
Fig. 270. Ship-worm, Teredo Norvegica, removed from its burrow. 
always bores in the direction of the grain unless it meets the 
tube of another Zeredo, or a knot in the timber.* In 1731-2 it 
did great damage to the piles in Holland, and caused still more 
alarm ; metal sheathing and broad-headed iron nails haye been 
found most effectual in protecting piers and ship-timbers. The 
Leredo was first recognised as a bivalye mollusc by Sellius, who 
wrote an elaborate treatise on the subject in 1733. (Forbes.) 
T. corniformis, Lamarck, is found burrowing in the husks of 
cocoa-nuts and other woody fruits floating in the tropical seas; 
its tubes are extremely crooked and contorted, for want of 
space. The fossil wood and palm-fruits (Nipadites) of Sheppy 
and Brabant are mined in the same way. The tube of the giant 
Teredo (7Z’. arenaria, Rumph. Furcella, Lamarck) is often a yard 
long and 2 inches in its greatest diameter; when broken across 
it presents a radiating prismatic structure. The siphonal end 
is divided lengthwise, and sometimes prolonged into two diverg- 
ing tubes. 7. Norvegica and 7’. nana are divided longitudinally 
and also concamerated by numerous, incomplete transverse 
partitions at the posterior extremity. 
LT. palmulata (Xylotrya, Leach) has the siphonal pallets elon- 
gated and penniform (Pl. XXIII, Fig. 28); a species with 
similar styles occurs in the fossil wood of the Greensand of 
Blackdown. . 
Distribution, 21 species. Norway, Britain, Black Sea; Tro- 
pics :—119 fathoms. 
Fossil, 24 species. Lias—. United States, Europe. 
Sub-genus. Teredina, Lamarck. 'T. personata, Pl. XXIII, 
Figs. 24,25. Eocene, Britain, France. Valves with an acces- 
sory plate in front of the umbones; free when young. The 
tube is sometimes concamerated; its siphonal end is often 
truncated ; and the opening contracted by a lining which makes 
it hour-glass shaped, or six-lobed (Fig. 25 a.). 
* The operations of the Teredo suggested to Mr. Brunel his method of tunnelling 
the Thames, 
