CONCHIEERA. 



255 



Xylopliaga dorsalis. 



genus Pholas are in this supplied by a kind of partition ; 

 the accessory valve is large and shield-formed. — 3 species ; 

 also fossil. 



Found living in the Philippines and W. Columbia. 



Xylophaga. Turton. — Shell, valves equal, inequi- 

 lateral, and very much gaping anteriorily ; 

 two small accessory testaceous pieces placed 

 near the hinge ; one small tooth in each 

 valve, with an internal rib running from 

 the boss to the margin. Animal, foot large 

 and pillar-shaped, occupying the greater part of the anterior 

 opening, and may be protruded to some length ; the 

 margin of the mantle plicated ; siphons very extensible, as 

 far as three-quarters of an inch.* — A few species. 



The shells of X. dorsalis are found in light wood, or 

 pieces of stick, which the animals penetrate to the depth 

 of about an inch, f X. globosa appears to differ but 

 slightly. 



Teredo. Lin, — Shell, attached to 

 the animal, valves gaping, and having a 

 long recurved tooth under the boss of 

 each ; the tube is long, irregular, and 

 open at both ends. Animal vermiform ; 

 mantle tubular, slightly open anteriorly ; 

 siphons very long, bifurcating at their ex- 

 tremities, orifice fringed; a muscular ring, 

 into which are inserted two variously shaped 

 calcareous pallets at the part where the si- 

 phons divide ; branchias continued into the 

 siphonal tube ; foot rudimentary, sucker 

 shaped. % — Many species ; also fossil. 



Teredo navalis, 



* Forbes's British Moll. 

 | Forbes's British Moll, 



| Reeve's Con. Sys. 



