Chap. 
fulcala. 
IV. 
CONCHOLOG7, 
4^3 
ovalis , 
rejlexa, 
cornea . 
bicornis. 
perforata. 
laBea, 
lagena. 
retorta. 
incmvata 
< 5 ? 
Teredo. 
navalis . 
*39. S. whirls 2, deeply and fpirally grooved ; green- 
ifh ; minute. Coalt of Pembrokefhire, on the roots of 
fucus digitalis. 
* 40. S. fuboval, with 2 bends, imperforated •, minute. 
Found at Denbigh. 
* 41. S. regular, rounded; margin refle&ed at the a- 
perture ; minute. Pembrokefhire fands. 
* 42. S. "regular, rounded, pellucid, with three whirls ; 
horny. > Pembrokefhire coafh 
* 43. S. femilunar, ventricofe, white, opaque, glofly ; 
minute. Sandwich and Reculver. 
* 44. S. white, opaque, glofly ; femilunar and perfo- 
rated ; minute. Sandwich. Rare. 
* 45. S. oval, thin, fmooth, pellucid, with milky veins ; 
minute. Sandwich ; very rare. 
* 46. S. round, ftriated, grooved, with a narrow neck, 
like an oil flafk ; minute. Sandwich and Sheppey. 
* 47. S. rounded, margined, with a (lender recurved 
neck. Sandwich ; rare. 
* 48. S. flraight, with 3 clofe whirls at the fmaller 
end ; minute. Sandwich, 
Gen. -35, Teredo. 
Gen. Char . — The animal is a terebella, with two cal- 
careous, hemifpherical valves, cut off before, and 
two' lanceolate ones ; the (hell tapering, flexuous, 
and penetrating wood. 
Species. 
1. T. Ship-worm ; (hell thin, cylindrical, fmooth ; 
more or lefs twilled ; rather obcufe at the tip ; 4 to 6 
inches long. 
At the fmaller end the (hell becomes thick and 
flrong, and is furnifhed within with plaits or laminse, 
which contract that part, leaving a very fmall opening. 
The anterior valves attached to the head of the animal, , 
are of a hemifpherical form, one half of the front pro- 
jecting in a (harp angle, and fomewhat pointed. The 
itifide of each valve is white, furnifhed with a long, 
flat, curved tooth, projecting inwards, under the hinge, 
and a fhort lateral tooth at the extremity of tire hinge, 
correfponding in each valve. The margin oppofite the 
hinge runs to an acute angle, at the point of which, in 
each valve, is a fmall knob, which comes in contact when 
the valves are brought together. Near the extremity 
of the tail there are two valves, one on each fide ; a 
little concave on the infide, and rounded at the end. 
By their means the extremity of the tube at the thick- 
ened part is clofed. Thefe are properly to be confider- 
ed as the fliell of the animal, becaufe they are attached 
to it. The tube, or teflaceous (heath, which lines the 
hole made in the wood, appears only to be formed as an 
apartment, in which the animal may move with more 
eafe ; for it is found that tw r o tubes never come in im- 
mediate contaCt with each other, although the fibres 
of the wood between them are frequently no thicker 
than paper. This tube 13 feldom fo long as the animal ; 
the internal part of the perforation is ufually not lined 
with it for the fpace of 2 inches, and fometimes more ; 
but the fmaller end is always even with the furface of 
the timber which is perforated ; but fo fmall, as not 
eafily to be difeovered, yet it is fufficient to admit the 
water, which is regulated by the pofterior valves of the 
animal. 
It is found in the fides and bottom of (hips, and even 
the ftrongefl oak, which has been fame time underwa- 
ter. This teflaceous animal was originally a native of 
the warmer climates, and was brought to Europe, 
where it has been produced, and has proved extremely 
deflrudlive to the bottoms of (hips, and to works con- 
flrudled of wood, which remain for fome time conflant 
ly under water. It appears, from fome piles of folid 
oak which were examined in the dock-yard of Ply- 
mouth, and which had remained under water for about 
four or five years, that the deftruftive effedts of thefe 
animals are very great in that time ; for thefe piles were- 
found to be greatly perforated, which rendered it ne 
cefiary to remove them, and replace them with others. 
The bottoms of (hips w hich frequent warm climates, it 
is well known, are (heathed with copper, to fecure them 
from the effedls of thefe deflruclive animals. But the 
method which is adopted about the dock-yards to pre- 
ferve the timbers which are conflantly under water, is 
to cover them with broad-headed nails ; which, by the 
effedls of the fea water are foon incrufted with a coat- 
ing of rufl, which is found to bei impenetrable to the- - 
(hip-worm. 
It lias been obferved that the teredo navalis cuts a 
crofs the grain of the wood as feldom as poftible. After 
it has penetrated a little way, it turns and continues- - 
with the grain, till it meets with another fhell, or a 
knot in the wood. The courfe which it then takes is 
regulated by the nature of the' obflrudlion. If this be 
confiderable, it makes a fhort turn back in the form of 
a fyphon, rather than continue for any diilance acrofs 
the grain. 
2. T. folid, cylindrical, undulated-. 7 inches long .utriculus. 
In wood. 
3. T. clavated at one end, incurved at the other ; clava. 
narrower, obtufe and perforated in the middle; 2 
inches long. Found in the feed-veffels of the xylofteuin 
granatum. 
Gen. 36. SaBELLA. Sabella. 
Gen. Char. — The animal a nereis, with a ringent motth, 
and two thicker tentacula behind the head ; fhell tu- 
bular, compofed of particles of fand, broken (hells, 
and vegetable fubftances, united to a membrane by 
a glutinous cement. 
Species , 
1. S. folitary, loofe, curved, with lentiform, glofly gra -fervpofa* 
nulations ; thicknefs of a fwan’s quill. India and A- 
merican iflands. 
3. S. folitary, fixed by the bafe, fimple, curved, with fcabra , 
radiated, rough granulations. America. 
* 3. S. numerous, parallel tubes, communicating by alveo!ata s 
an aperture, forming in the mafs the appearance of 
honey combs ; 2 to 3 inches long. European coafts, 
Britain. 
* 4. S. folitary, fuhcylindrical, papyraceous, chiefly chryCedcc, 
compofed of fragments of (hells, thicknefs of a quill ; 
2 to 6 inches long. European and Indian feas, fhores 
of Britain. 
* 5. S. flraight, conic, compofed of minute particles of be/gica, 
fand ; 2 to 3 inches long. European coafts, (bores of 
Britain. 
6. S. brown, with alternate white and black rings ; re&anguta* 
flraight, with a reftangular gibbous extremity 7 9 inches 
long. 
7-3 - 
