296 Zoological Society : — 



line, and these holes appear to be filled up by an internal coat when 

 the animal absorbs the end and lengthens its tube. 



The larger end of the tube is entirely closed over by two convex, 

 arched, shelly laminae, continuous from each side of the tube, and 

 meeting and slightly overlapping one another in the central line, 

 which is opposite to the septum between the two tubes in the smaller 

 end of the shell-sheath of the animal. 



These small holes are evidently intended for admission of water 

 to the animal, and the shelly septa at the bottom to protect it from 

 the sand in which it lives. The holes are similar to the tubes of 

 Penicillus aqitarius and Clavagella, which live in sand, and Bryopa 

 melitensis, which lives in porous stone. 



I have not observed any similar perforations in the tube of the 

 Teredo ; and indeed they would not be of any use, as the tube is 

 deeply sunk in the substance of the wood in which the animal burrows. 



The Teredines appear during their period of rest to close the end 

 of their tube, with a shelly septum formed of a single convex plate. 

 There are two fragments of tubes in the British Museum which ap- 

 pear to belong to that genus, from their external appearance and 

 prismatic structure, which are so closed at the bases : in one speci- 

 men the closing septum is uniformly convex, and like the tube-struc- 

 ture ; in the other the septum is divided into two equal portions by a 

 transverse groove or depression ; but on neither of the specimens can 

 I observe any traces of the septum being formed of two plates over- 

 lapping in the middle like the septum of Furcella. 



The calcareous tubes o^ Septaria, mentioned bv Home, Phil. Trans. 

 1806, p. 27 Q, Dillwyn, R. Shells, ii. p. 1088, and in the 'Mag. Nat. 

 Hist.' 1838, p. 408, as having a succession of sejjfa, proved on re- 

 examination, Mr. Woodward informs me, to be the shells of Vertneti. 



The character of the family Teredinidcs is, that the animal 

 always lives in a tube ; that it is provided with two appendages, 

 one on each side of the siphons, called palettes, which differ consi- 

 derably in structure in the different genera ; and that the front of 

 the body of the animal over the mouth is encased in two very small 

 valves like those of a Pholas in structure and form, but in a more 

 rudimentary state of development ; the tubular case of the animal 

 apparently taking the place, or being in fact a great development of 

 the dorsal additional shelly plate usually found more or less deve- 

 loped in the different genera of PholadidcB. 



Now it is clear that by Pallas, Home, and Messrs. Adams referring 

 this shelly tube to the genus Teredo, they believed that it had all 

 these peculiarities. 



I was, therefore, very much pleased when a perfect specimen of 

 this interesting genus came into my hands ve.sterday, to think that 

 I might have the opportunity of bringing before the Society the pa- 

 lette and valves of this genus, which until now have been desiderata, 

 especially as the sound made by shaking the tube showed that some 

 shelly pieces were contained ithin it. 



But on making a small aperture on the side near the base of the 

 tube to examine the structure of the valves, I was astonished to find 



