96 Marine Shells of the Western Coast of Florida 



themselves to some wooden structure and begin excavation of the 

 long tunnel which is to be the permanent home. There is evidence 

 that the wood boring is effected by use of the shell as a file, and also 

 that the accumulation of sawdust is ingested by the shipworm and 

 has some food value. The burrows are long and follow the grain of 

 the wood except at the point of entrance and where another burrow 

 or a knot is encountered. 



The anterior, shell-bearing portion of the mollusk's long body 

 lies at the bottom of the burrow; the siphon end is at the opening, 

 and when complete, the burrow is smoothly lined with an adven- 

 titious, calcareous tube. 



The shell is white, globose and gaping, its external surface bears 

 many diversely sculptured teeth. The posterior end of the mollusk 

 bears a pair of calcareous structures called pallets, which may be ad- 

 vanced or withdrawn to close or open the mouth of the tube. Charac- 

 ters of the shell and distinctive features of the pallets are necessary 

 factors in differentiating species. Reference to a collection is necessary 

 for specific determination. 



Genus TEKEBO Linne, 1758 

 TeredoiGs floridania Bartsch PI. 45, figs. 313, 314 



Shell small, nearly round, white. The two halves gape widely, 

 the foot extending through the anterior side, and the long wormlike 

 body through the posterior side. There are three parts to the shell: 

 the lobe, the disc and the auricle. The umbo is smooth; the remaining 

 portion of the lobe is denticulated. The anterior portion of the disc 

 is broad and more coarsely denticulated than the lobe. The middle 

 and posterior portions of the disc are smooth. The auricle is small, 

 smooth, being marked only with growth lines, and is joined to the 

 margin of the posterior disc. It is covered by the mantle in living 

 specimens. On the interior are the condyles, calcified prominences, 

 one dorsal and one ventral. These condyles meet in the two valves, 

 forming a double hinge, upon which the two valves move back and 



^®8 Lat, teredo, teredinis, a worm. 



