PELECYPODA 



599 



T. navalis L. (Fig. 945). Length of tube usually 25 cm. or less, but 

 sometimes much greater; diameter of tube 6 to 10 mm.; length of shell 

 6 mm. ; width 2 mm. ; posterior lobes of shell much larger than the anterior ; 

 pallets rounded on one side and flat on the other, with the stalk and 

 blade of equal length : Arctic seas to Texas ; very common ; Europe. 



T. megotara Hanley (Fig. 946). Length of tube up to 45 cm.; 

 length and height of shell 6 to 12 mm. ; length of pallet 6 mm. ; width 3 

 mm.; posterior lobe large and separated from the umbo by a narrow, 

 deep, rounded notch ; stalk of pallet half as long as blade, which is obo- 

 vate: Arctic seas to South Carolina; common in floating wood; Europe. 



Fig. 945 



Fig. 946 



Fig. 945 — Teredo navalis (Verrill). 1, ends of the siphons; 2, pallets; 3, mus- 

 cular collar by which it adheres to the tube ; 4, posterior lobe of shell ; 5, foot ; 

 6, anterior lobe of shell. Fig. 946 — Teredo megotara (Gould). 1, shell; 2, pallets. 



T. norvegica Spengler. Tube up to 30 cm. long and chambered at 

 entrance ; length of shell 14 mm. ; height 15 mm. ; length of pallet 21 mm. ; 

 width 6 mm.; anterior and posterior lobes of shell of about the same 

 length; pallets with stalk and blade of equal length, the latter being 

 truncate: New York to west coast of Florida; Europe 



T. thompsoni Tryon. Length of shell 9 mm. ; 

 height 12 mm.; anterior and posterior lobes of 

 equal height ; length of pallet 8 mm. ; width 3 mm. ; 

 blade of pallet oval and much longer than the 

 stalk: Cape Cod to Florida; sometimes common. 



T. chlorotica Gould. Bun-ows very small, 

 lying across the grain of the wood and close 

 together so as to resemble a honeycomb; length 

 and height of shell 3 mm.; pallet, paddle-shaped, 

 5 mm. long: Massachusetts Bay to Florida. 



2. Xylotrya Leach. Pallets long and 

 feather-.shaped, the blade consisting of articulated 

 pieces radiating obliquely from the stalk : 10 species. 



X. fimbriata Jeffreys (Fig. 947). Shell similar to that of Teredo 

 navalis; length of pallet 12 mm. ; width 2 mm. ; tubes 30 cm. or more long : 

 Massachusetts Bav to Florida : often common. 



Fig. 947 — Xylotrya fim- 

 briata (Gould). 1, shell; 

 2, pallets. 



