92 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [386] 
cup-shaped layer of shelly matter, continuous with the lining of the 
tubes, and closing up the burrow in front of its shell; sometimes it 
retreats and forms a second partition of the same kind. 
This species produces its young in May and probably through the 
greater part or allof the summer. The eggs are exceedingly numerous, 
probably amounting to millions, and they are retained in the gill-cavity, 
where they are fertilized and undergo the first stages of their development. 
The embryos pass through several curious phases during their growth. 
In one of the early stages they are covered with fine vibrating cilia, by 
means of which they can swim like ciliated infusoria; later they lose 
these cilia and develop a rudimentary bivalve shell, which is at first 
heart-shaped, and the mantle begins to appear and larger retractile 
cilia develop upon its edge, which serve as organs for swimming; but 
at this period the shell is large enough to cover the whole body when 
contracted. In this stage they swim actively about in the water ; later 
the cilia become larger, a long, narrow, ligulate foot is developed, by 
means of which they can creep about and attach themselves temporarily 
to solid objects; the shells become rounder, a pair of eyes and organs 
of hearing are developed; after this the little animal begins to elongate, 
the locomotive cilia are lost, the eyes disappear, and the mature form is 
gradually assumed. These young Teredos, when they finally locate upon 
the surface of wood-work and begin to make their burrows, are not 
larger than the head of a pin, and consequently their holes are at first 
very minute, but owing to their rapid growth the holes quickly become 
larger and deeper. 
This species is very abundantalong the southern coast of New England, 
from New York to Cape Cod, wherever submerged wood-work, sunken 
wrecks, timber buoys, or floating pieces of drift-wood occur. It alsoinfests 
the bottoms of vessels not protected by sheathing. It is not confined to 
pure sea-water, but occursin the piles and timbers of our wharves in har- 
bors that are quite brackish. Thavefounditabundantin the piles of Long 
Wharf in New Haven Harbor, where the water is not only quite brack- 
ish, but also muddy and contaminated with sewerage and other impuri- 
ties. At Wood’s Hole it was found to be very abundant in the cedar 
buoys that had been taken up from various localities and placed on the 
wharves to dry and be cleaned. Captain B. J. Edwards informed me that 
formerly, when the buoys were not taken up, they would not usually last 
more than two years, owing chiefly to the attacks of this TYeredo, but 
under the present system there are two sets of buoys, which are alter- 
nately taken up and put down every six months. After a set has been 
taken up and allowed to dry thoroughly they are scraped to remove the 
barnacles, &c., and then receive a thorough coat of verdigris paint, 
each time, before they are put down. With this treatment they will 
last ten or twelve years, but they are more or less perforated and in- 
jured every year, until finally they become worthless. Inasmuch as the 
Teredos produce their young all through the summer, and they develop 
