TEREDID^. 121 



three-lobed, concentricall}'' striated, and with one transverse 

 furrow ; hinge-margins reflected in front marked by the anterior 

 muscular impressions ; umbonal cavity with a long, curved, 

 muscular process. 



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

 with a minute pedal opening ; foot sucker-like, with a foliaceous 

 border; viscera included in the valves, heart not pierced by 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 bifurcation and furnished with two shelly pallets 

 or styles ; orifices fringed. 



T. navalis is ordinarily a foot long, sometimes two and a half 

 feet ; it destroys soft wood rapidly, and teak and oak do not 

 escape; it usually bores in the direction of the grain, unless it 

 meets the tube of another Teredo or a knot in the timber. In 

 1*731-2 it did great damage to the piles in Holland, 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 recognized as a bivalve moUusk 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. 



T. Norvegica and T. nana are divided longitudinally and also 

 concamerated by numerous, incomplete, transverse partitions at 

 the posterior extremity of the tube. 



I annex Dr. J. Gwyn Jeff'reys' excellent account of this 

 moUusk : 



" The Teredo is an anomaly. It consists of a long and 

 nearly gelatinous worm-like body, without rings or segments, 

 terminating at one end in a pair of hemispherical valves, that 

 somewhat resemble the two halves of a split nutshell which has 

 had a large slice cut off at each side, and at the other end in a 

 pair of symmetrical shelly paddles with handles of different 

 lengths, which close this extremity at the will of the animal. 

 The open part of the bivalve shell is placed at the further end, 

 and receives a circular disk, of a fleshy or rather muscular 

 nature, which may be termed the foot ; this is the broadest or 

 widest part. Inside each valve is seen a curved process, like a 

 bill-hook, that projects from the hinge at a right-angle. The 

 shell covers and protects the mouth, palps, liver and other deli- 

 cate organs. The body tapers gradually to the outer or nearer 

 end, where it becomes quite small and attenuated ; it contains 

 the gullet, intestines and gills, and is enveloped in a thin mem- 

 brane or mantle, which forms at the outer end two cylindrical 

 9 



