TEREDO NAVALIS IN NOVA SCOTIA — MURPHY. 363 
one quarter to half a millimetre, it enlarges little by little, until 
it reaches a diameter of five millimetres and more; as regards 
his length, and consequently that of the tube which incloses him, 
we have sometimes found it to be thirty to forty centimetres. 
He never goes upward more than half way between the flow 
and ebb of the tide; although the teredo is thus, for a short 
time, partially above the water, yet it appears that the wood 
holds a sufficient amount of moisture to sustain his life tempo- 
rarily. 
“ The researches of Kater have still further shown, what had 
already been remarked by Sellius, that the Teredo can hibernate 
in the wood, and that it is those individuals, thus preserved,which 
in the spring go through with all the phenomena of reproduction 
—i.e., the formation of eggs, fecundation, development, and ex- 
pulsion of the yeung. 
“The part of the external integuments which constitutes the 
mantle deposits a calcareous matter, forming an interior lining 
to the gallery in the wood (fig.12. f.) Between this calcareous cas- 
ing and the body of the animal there remains a space sufficient 
to prevent any inconvenience, at least during the act of respira- 
tion, for it is possible that when the Teredo absorbs water, which 
serves for respiration, his body is distended, and fills exactly the 
calcareous tube. The form of this tube, secreted little by little, 
corresponds exactly with that of the gallery, which has been 
slowly perforated in the wood; it has the appearance, also, of a 
séries ef rings placed one against the other. As the animal pro- 
gresses a new ring is added to those which existed before, so that 
when the tube is closed at its extremity by a calcareous film, its 
length represents the total length of the animal. (fig. 12; b to c) 
Among the segments of the tube, those which are nearest the 
surface of the wood are the oldest and hardest; in the interior 
of the woed, where the gallery ends (fig. 12, g), the calcareous 
ring, newly formed, is at first soft, flexible, and of slight consist- 
ency ; later, it becomes solid, and closes up the tube, as has been 
remarked by Sellius, 
“The calcareous tube, once formed, constitutes for each Teredo 
his own abode, where he isolates himself from his companions, 
