330 MANUAL OF THE MOLLUSCA. 



Fig. 223. Ship-worm, Teredo Norcegica, removed from its burrow. 



Animal worm-like ; mantle-lobes united, thickened in front, with a 

 minute pedal opening ; foot sucker-like, Avith a foliaceous border ; viscera in- 

 cluded in the valves, heart not pierced br the intestine; mouth with palpi ; 

 gills long, cord-like, extending into the siphonal tube ; siphons very long, 

 united nearly to the end, attached at the bifm'cation and furnished with 2 

 shelly pallets or styles ; orifices fringed. 



T. navalis is ordinarily a foot long, sometimes 2^ feet; it destrovs soft 

 wood rapidly, and teak and oak do not escape ; it always bores in the direc- 

 tion of the grain unless it meets the tube of another Teredo, or a knot in the 

 timber.* In 1731-2 it did great damage to the piles in HoUand, and 

 caused still more alarm ; metal sheathing, and broad-headed iron nails have 

 been found most effectual in protecting piers and ship-timbers. The Teredo 

 was first recognised as a bivalve mollusc by Sellius, who wrote an elaborate 

 treatise on the subject, in 1733. {Forbes.) 



T. corniforrnis. Lam. 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 {T. arenaria, Rumph. Purcella, Lam.) is often a yard long 

 and 2 inches in its greatest diameter ; v,-hcn broken across it presents a radi- 

 ating prismatic structui-e. The siphonal end is divided lengthwise, and some- 

 times prolonged into two diverging tubes. T. Norvegica and T. denticitJata 

 ai'e divided longitudinally and also concamerated by numerous, incomplete 

 transverse partitions, at the posterior extremity. 



T. bijjalnmlata (Xylotrya, Leach) has the siphonal pallets elongated and 

 penniform (PI. XXIIL fig. 28) ; a species with similar styles occurs in the 

 fossil wood of the Green-sand of Blackdown. 



Bistr. 14 sp. Norway, Brit. Black Sea; Tropics: — 119 fins. 



Fossil, 24 sp. Lias — . IT. States, Europe. 



Sub-genufi, Teredina, Lam. T. personata, PI. XXIII, figs. 24, 25. 

 Eocene, Brit. Prance. Valves with an accessory plate in front of the um- 

 bones ; free when young, united by their margins to the shelly tube when 

 adult. The tube is sometimes concamerated ; its siphonal end is often trun- 

 cated ; and the opening contracted by a lining which makes it hour-glass 

 shaped, or six-lobcd (fig. 25a.). 



* The operations of the Teredo suggested to Mr. Brunei his method of tunnelling 

 the Thames. 



