TEREDINES. 331 



The species of this genus are usually found boring in 

 floating timber and drift-wood. M. rivicola was discovered 

 by one of the Authors perforating floating logs used as 

 landing-places at Gunung Taboor in Borneo, twelve miles 

 from the mouth of the river Pantai, where the water was 

 perfectly fresh. 



Species of Martesia. 



aperta, Sow. multistriata, Sow. 



australis, Gray. obtecta, Sow. 



brancbiata, Gould. ovum, Gray. 



calva, Sow. rivicola, Sow. 



cuneiformis, Say. striata, Linn. 

 curta, Soiv. 



Sub-fam. TEKEDININ^E. 



Animal worm- like. Siphons furnished at their extremi- 

 ties with two shelly styles or pallettes. Umbonal muscle 

 covered only with a coriaceous epidermis, and not protected 

 by shelly accessory valves. 



Living at the inner extremity of a burrow partly or 

 entirely lined with shell. 



Genus TEREDO, Linnams. 



Siphonal styles simple, oblong, transverse, entire 

 Shell globose, gaping anteriorly and behind; valves tri- 

 lobate, concentrically striated, divided by a single, transverse 

 groove; hinge-margins inflexed anteriorly; interior of valves 

 furnished with a long, curved process for the attachment of 

 the pedal muscle. 



Tube sub-cylindrical, hard, shelly, divided longitudinally, 



