CONCHIFERA. 



Shell haying tlie form and ornamentation of Xylophaga, but 

 possesses an oblique internal postero-dorsal ridge; burrows, 

 apparently, without a shelly lining. 



Mahtesia (see p. 505). Sub-genus, Diplofhyra, Tyron, 1862. 

 D. Smithii, Staten Island, burrowing in oyster-shells. 



Shell with a double accessory valve ; the principal plate 

 directly over the umbones, with a smaller anterior one adjoin- 

 ing. 



Teredo (see p. 506). Sub-genus, Calolates, Gould. {T. 

 furcelloides, Gray). Siphonal palettes large, long, stilt-shaped , 

 siphons adherent, only becoming free at the tips. 



Disfrihution, 2 species. Burmack, Australia. 



Nausitora, Wright, 1864. N. Dunlopi (freshwater, India). 

 Siphonal palettes, outer surface convex, covered with thick 

 scale-like striae, inner Hat or slightly concave. 



Distribution, 2 species, burrowing in wood. Bengal. Aus- 

 tralia. 



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