606 ma:xual of the moltxsca. 



M. teredhu'/ormis was found in cakes of floating wax on llio 

 coast of Cuba. (G. B. Sby.) M. australis in (fossil r) resin, on 

 the coast of Australia. M. rivicola in timber twelve miles from 

 the sea, in Borneo. 31. scuUda, Eocene, Paris, linos its buiTow 

 with, shell. 



Jouannetia (semicaudata), Desm. (Pholadopsis, Conrad ; 

 Triomphalia, Sby.) Shell very short, sub-giobose ; right valve 

 longest behind ; anterior opening closed by a callous plate deve- 

 loped from the left valve overlapping the margin of the right 

 valve, and fixed to the single un symmetrical umbonal plate. 

 DistrihuUon, 4 species. Philippines, "Western America. Fossil, 

 Miocene — . Prance. 



Parapliolas, Conrad. P. bisulcata, PL XXIIL, Pig. 22. Valves 

 with 2 radiating furrows. Bistrihution, 4 species. Panama, 

 Torres Straits. 



Xylopiiaga, Turton. 



EtymoJocjy, xulon, wood, j^Jiago, to eat. 



Types, X. dorsalis, PL XXIIL, Pig. 23; X. globosa, Sby. 

 Valparaiso. 



Shell globular, with a transverse furrow ; gaping in front, 

 closed behind ; pedal processes short and curved ; anterior 

 margins reflected, covered by 2 small accessory yalves ; buiTOW 

 oval, lined with shell. 



Animal included within the valves, except the slender con- 

 tractile siphons, which are furnished with pectinated ridges, and 

 divided at the end ; foot thick, very extensile. 



DistrihuUon, 2 species. Norway, Britain, South America. 

 Bores an inch deep, and across the grain, in floating wood, and 

 timbers which are always covered by the sea. 



Teredo (Pliny), Adanson. 



Type, T. Norvegica, PL XXIIL, Pigs. 26, 27. 



Synonyms, Septaria, Lamarck. Ilyperotis, Guettard. 



Shell, globular, open in fiont and behind, lodged at the inner 

 extremity of a burrow partly or entirely lined with shell ; valves 

 3 lobcd, concentrically striated, and with one transverse furrow ; 

 hinge-margins reflected in front marked by the anterior muscu- 

 lar imjDressions ; umbonal cavity with a long curved muscular 

 process. 



^niwaZ worm-like ; mantle-lobes united, thickened in front, 

 with a minute pedal opening; foot sucker-like, with afoliaceous 

 border ; viscera included in the valves, heart not pierced by the 

 intestine; mouth with X)alpi; gills long, cord-like, extending 



