386 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



cup-shaped layer of shelly matter, continuous with the lining of the 

 tubes, and closing up the burrow in front of its shell 5 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 all of 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 5 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 Avater j later 

 the cilia become larger, a long, narrow, ligulate foot is developed, by 

 means of w hich they can creep about and attach themselves temporarily 

 to solid objects 5 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 abundant along the southern coast of New England, 

 from New York to Cape Ood, wherever submerged wood-work, sunken 

 wrecks, timberbuoys, or floating pieces of drift- wood occur. It also infests 

 the bottoms of vessels not protected by sheathing. It is not confined to 

 pure sea-water, but occurs in the piles and timbers of our wharves in har- 

 bors that are quite brackish. I have found it abundant in 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 Teredo, but 

 under the present system there are two sets of buoys, which are alter- 

 nately taken uj) and put down everj^ six months. After a set has been 

 taken ui) 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 linally they become worthless. Inasmuch as the 

 Teredos produce their young all through the summer, and tiiey develop 



