PERFORATIONS OF MARINE ANIMALS. 51 
and foreign seas, of those of the widely distributed genus Teredo. 
As a rule, every piece of wood from the wrecks of ships and 
boats on the eastern coast, and which has lain for some time on 
the bottom, is riddled by T'’eredo, and occasionally by Xylophaga. 
Their development seems to be such as to spread them rapidly 
and widely over large areas. The minute larval forms (in 
Teredo) are found in the branchial cavities in June, and in the 
middle of July the young, though very small, are fully formed. 
In September they penetrate the wood. It is further stated that 
these minute forms often fix themselves to a piece of wood so 
thin that development can only take place up to a certain size, 
when all must perish. This is thought by some to be a provision 
for keeping their increase in check, but such is probably in- 
appreciable. 
In regard to the hard parts, the globular valves agree with 
those in Xylophaga, being helmet-shaped and sculptured in a 
remarkable manner, so as to present a file-like surface, the 
function of which, not a few observers consider, is to aid in per- 
forating the wood. There are no shelly plates or shields such as 
occur in Xylophaga, but attached to the muscular ring at the 
base of the siphons are a pair of pallets, which are useful to 
zoologists in discriminating the species, and to the animal for 
protection. Thus when alarmed it withdraws its long siphons 
within the shelly tube, and guards the aperture by folding the 
calcareous pallets over the tip, just as the annelid, Lagis koreni, 
does with its broad golden bristles. T’eredo more readily accom- 
plishes this by the presence of ledges projecting from the narrow 
or outer end of the shelly tube, which is a secretion of the 
mantle. 
The food of the T'eredo consists of Diatoms, Infusoria, and 
other minute pelagic plants and animals which abound in all 
climes in the sea. It is only necessary to drag a tow-net a 
little distance below the surface of any of our bays (either in 
Summer or winter) to find an abundance of minute forms— 
amply sufficient to nourish these and other marine animals. 
The shipworm thus has no need to depend for subsistence on the 
minute particles of wood which it swallows, though, like the 
Swedish peasants with their Bergmehl, or the eaters of clay in 
North America, such doubtless increases the bulk of the food. 
