253 



ADDENDA. 



XYLOPHAGA—TC «TOiV. 



Testa ovato-globosa, tequivalvis, antice hiantissima, postice 

 claiisa, accessoriis cardinalibus instrueta. Cardo edentulus 

 infra marginem. Ligamentum mdlum. 



Shell globular-oval, equivalve, very open at the anterior side and 

 closed behind, furnished with accessorial valves about the hinge. 

 Hinge without the long curved tooth under tlie margin. Li- 

 gament none. 



XyLOPHAGA. doisalis. 



Tab. nost. 2, fig. 4 and 5. 

 Teredo dorsalis. Turton, Conch. Diet. p. 185, and p. 16 of this 

 work. 

 We have lately had opportunities fully to examine and elu- 

 cidate this new and interesting genus, important as it adds to our 

 knowledge of those singular inhabitants of wood and stone, essen- 

 tially differing from all other bivalves, in being furnished with 

 accessorial valves or appendages, and which additional valves 

 appear to stand as substitutes for the permanent ligament. 



