CONCHIFERA. 
Shell haying the form and ornamentation of Xylophaga, but 
possesses an oblique internal postero-dorsal ridge; burrows, 
apparently, without a shelly lining. 
MARrrTESIA (see p. 505). Sub-genus, Diplothyra, 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, Calobates, Gould. (7. 
furcelloides, Gray). Siphonal palettes large, long, stilt-shaped , 
siphons adherent, only becoming free at the tips. 
Distribution, 2 species. Burmack, Australia. 
Nausitora, Wright, 1864. N. Dunlopi (freshwater, India). 
Siphonal palettes, outer surface convex, covered with thick 
scale-like striae, inner flat or slightly concave. 
Distribution, 2 species, burrowing in wood. Bengal. Aus- 
tralia. 
31 
