VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. ' 379 



the outer surface of the wood, rendered soft by lying in the water, made the 

 aforesaid holes, and through them worked their way into the substance of the 

 wood. 



A small style of whalebone or lead, thrust into these small holes, runs 

 straight into them for 3 or 4 lines, so that its outer end always makes a right 

 angle with the pile : but afterwards, if the style be gently pushed forward, it 

 does not continue in the straight line, but runs either way, generally upward. 



But if one of these piles be split lengthwise, with a hatchet or wedge, it is 

 found full of passages, or hollow cylindrical ducts, each of which contains a 

 worm, surrounded with a thin testaceous substance, exactly filling the ductj, 

 and forming its involucrum or sheath, in which it can move with freedom. 



The ducts, beginning at the outer surface by a narrow hole, grow gradually- 

 wider, and run either straight, oblique, upward or downward. But what is 

 most surprising, these ducts never run into each other, nor communicate; but 

 each continues separate for every single worm. Over the worm's head there 

 are 2 or 3 drops of a salt liquor, thicker than water, but not the least appear- 

 ance of the dust of the corroded wood. 



Whence it appears, that all the vvood, which had before filled up the place 

 of the duct, in which the worm with its covering is now found, was eaten 

 and consumed by the worm : and as it seems quite incredible, that an ani- 

 mal, which appears soft, and almost as fluid as the white of an egg. should 

 be able to eat through such hard wood; the description of this xylophagous 

 worm is offered to the Royal Society, in order to give them some knowledge 

 of this water-insect, which has done so many millions damage to these 

 countries. 



They are found of various sizes and thickness. There are some of the 

 younger ones not above an inch or two in length ; some of a middle size, such 

 as represented in figures 6 and 7, pi. 8 ; and some 13 or J 4 inches long. 



But in order to a more accurate description, we will divide the animal into 

 head, body, and tail. 



The head is of a most wonderful structure, being covered with two hai-d 

 shells or hemicrania, of a substance neither testaceous nor osseous, securing 

 their softer contents : and being viewed through a microscope, they appear as 

 in fig. 8, as well as they could be drawn. These hemicrania are two white bodies, 

 much harder than the substance which forms the testaceous covering ; the 

 inner surface hollow and smooth ; the outer, convex and rough, with 3 fibres 

 running different ways ; and both together perfectly represent a double bit, of 

 that kind of borer, called an auger, 



3 Ci 



