122 TEREDID^. 



tubes (siphons), mostly of unequal length. The larger tube 

 (siphon) takes in infusoria or similar animalcules, which consti- 

 tute the food of the Teredo, as well as imbibes water charged 

 with air for the purpose of respiration and keeping the whole 

 fabric moist; while the smaller tube is employed to eject the 

 water which has been exhausted or deprived of its aeriferous 

 qualities, and also serves to get rid of the woody pulp that is 

 excavated by the Teredo. Both tubes form a kind of hydraulic 

 machine. At the base of each lies one of the paddles, often 

 termed ' pallets,' and which may be translated into scientific 

 language as 'claustra.' When the Teredo is alarmed or not 

 feeding, it withdraws its tubes into the neck of its sheath or 

 shelly cylinder ; and the pallets, which had been previously kept 

 pressed against the sides, then spring forward and close the 

 opening, so as to form an efficient barrier against all foes, whether 

 Crustacea or annelids. This complicated animal mechanism is 

 entirely enclosed in the sheath or cylinder above mentioned, 

 which is secreted by the mantle, and varies considerably in 

 thickness and extent. The inside of the sheath is, at its outer 

 or narrower end, divided into short strips or ledges, arranged 

 in an imbricated fashion ; the last-formed of these ledges serves 

 as a point d^appui for the blades of the paddles, and it greatly 

 assists the Teredo in closely shutting its doors. The whole of 

 what I have above endeavored to describe is found only within 

 some hard vegetable substance, either the hull of a vessel or boat, 

 a harbor pile, a shipping-stage, a floating tree or the roots of one 

 growing on the banks of an estuarine river. The food of the 

 Teredo consists entirely of minute organisms, that are introduced 

 with the water into the incurrent or branchial tube, and it does not 

 consume the wood as any part of its nourishment. Nor do I 

 believe that the eroded material undergoes any chemical change, 

 either in the stomach of the Teredo or in the passage outwards 

 through the intestine, although in the latter receptacle it is 

 closely compressed. When it is voided or expelled by the 

 excurrent tube, and separated in the water, it becomes a floccu- 

 lent mass of pulp, like that of paper, composed of extremely 

 minute and fine particles of an irregular size and shape, but still 

 retaining its fibrous structure. It does not exhibit any appear- 

 ance of having been digested." 



' CALOBATES, Gould, 1862. Siphonal pallets large, long, stilt- 

 shaped, siphons adherent, only becoming free at the tips. T. 

 furcelloides, Gray. 2 sp. Burmack, Australia. 



NAUSiTORA, Wright, 1864. Siphonal pallets, outer surface 



convex, covered with thick scale-like strise, inner flat or slightly 



concave. N. Dunlopi (fresh-water, India). 2 sp. Burrowing in 



wood. Bengal, Australia. 



: LYRODUS, Gould. This name is given for a small American 



