T H O T H R 
It is generally fuppofed by the moderns, that 
the Tettigonia was the fame with the infeft which 
the French denominate cigalon ; and Reaumur 
obierves, that whereas die ancients were ac- 
quainted with only two fpecies, we are v/ith three ; 
and that our middle-fized cicada was their Tet- 
tigonia. 
^TEUCHTLACOT-ZANHQUI. An Ame- 
rican appellation for the rattle-fnake. 
TEUTHIS. A genus of the abdominal fifhes : 
the characters of which are ; that the head is a 
little truncated on the fore part; that the bron- 
chial membrane has five rays ; and that the teeth 
are equal, rigid, and clofe fet, forming a regular 
feries. 
Linnseus enumerates only two fpecies. 
THEDO. An appellation by which fome 
ichthyologies exprefs the trout. 
THISTLE-FLY. A fmall infeft produced 
from a fly-v/orm, which hatches in the protube- 
rances of the carduus hremorrhoidalis. In the 
protuberances of this thiflle, while they are clofed 
in all parts, the worm of this fly undergoes it's 
lafb transformation: it here makes a fhell of it's 
own fkin, in form of an egg, within which it af- 
fumes the nymph flate. When this nymph be- 
comes a living fly, the leaft part of it's difficulty 
confifts in emancipating itfelf from the fliell : it 
has a ftronger prifon from which it mjuft get free, 
namely, the clofe compafted fibres of the protube- 
rance of the vegetable. It has, however, no other 
way of performing this difficult tafl< but that of in- 
flating it's head, and throwing out the bladder or 
muzzle with which it is provided in this ftage of 
it's exiftence. 
THORACIC!. In the Linnsan fyftem, the 
name of the third genus of bony fifhes, which re- 
ipireby the means of gills only: the charafter of 
which is, that the ventral fins are placed under- 
neath the pe£lorai ones. 
This order includes feventeen genera, and two 
huntired and eighteen fijecies. The genera are 
thefe: the cepola, echeneis, coryphjena, gobius, 
cottus, fcorpsena, zeus, pleuroneftes, ch^todon, 
fparus, labrus, fcijena, perca, gafterofteus, fcom- 
ber, mullus, and trigla. 
THORNBACK; the Raia Clavata of Lin- 
naeus. A fpecies of ray eafily diftinguifhed from 
all the other by the rows of ftrong fharp fpines 
difpofed along the back and tail. In large fpeci- 
mens, there are ibmetimes three rows on the back, 
and five on the tail, all inclining towards it's end. 
On the nofe, and on the inner fide of the fore- 
head, near the eyes, there are a few fpines j and 
others are fcattered, without any regularity, on 
the upper parr of the perioral fins. The mouth 
is fmall, and replete with granulated teeth. The 
upper part of the body is of a pale afli-colour, 
marked with fliort flreaks of black ; and th.e fkin 
is rough, with fmall tubercles like fhagreen. The 
belly is white, croffed with a fl;rong femilunar car- 
tilage beneath the Ikin: in general, the lower part 
is fmooth, having only a few fpines on each fide. 
Young fiih have very few fpines on them; and 
their backs are often fpotted with white, each 
fpot encircled with black. 
The Thornback frequents the fandy fhores of 
Britain-, is extremely voracious, feeding, on all 
forts of flat fiffi; but is particularly fond of her- 
rings and fand-eels; and fometimes devours cruf- 
taceous animals, fuch as crabs. It begins to ge- 
nerate in June; and brings forth it's young in 
July and Auguft, which, as well as thofe of the 
fixate, obtain the name of maids before they are 
old enough to breed. This filli begins to be in 
feafon in November, and continue^ fo for fome 
months; but it's young, as well as thofe of the 
flcate, are in feafon throughout the whole year. 
The Thornback fometimes weighs fourteen or 
fifteen pounds; and has even been known to ex- 
ceed that weight. 
THOS. An animal of the \vo\{ kind, com- 
mon in Surinam. It is larger than the common 
kind; has a light bent tail, and a white belly, it 
never touches men or cattle; provides it's food 
rather by cunning than open force; and preys 
chiefly on poultry and water-fowl. 
THRESHER. An appellation fom.etimes 
denoting the fea-fox. 
THRIPS. A name whereby the ancients ex- 
prefied a fort of w^orm hatched from the egg of a 
beetle; which, while in the v/orm fl;ate, eats it's 
way into v/ood, wherein it forms cells and cavi- 
ties of various fliapes, and in various direftions. 
In the Linnjean fyflem, the Thrips is of the or- 
der of hem.iprera. It's characters are thefe: the 
rollrum is fmall and obfcure ; the antennae are as 
long as the thorax; the body is ilender, and of an 
equal thicknefs; the abdomen is rcflexible, and 
often bent upwards; anc. the four wings are ex-- 
tended, incumbent, narrow, and crofs each other 
at fome difcance from the bafe. The Thrips has 
alfo fix feet, and the tarfus of each foot has only 
two articulations. 
Thefe infeCls are found on many plants and 
flowers, and efpecially peaches and neClarines. 
THRISSA. An appellation by which the 
Greeks, and fome of the m.odern Latin writers, 
exprefs the fifli known in England by the name 
of the fliad, or mother of herrings. 
THROSTLE; the Turdus Muficus of Lin- 
naeus. This bird, called alfo the fong-thrufh, 
or mavis, and fometimes the turdus vifcivorus 
minor, is about nine inches in length, and thirteen 
and a half in breadth. It fo nearly refem.bles 
the miflTei-thrufii in colour, that nothing more 
need be remarked, than that it is inferior in fize, 
and that the inner coverts of the v/ings are yellow. 
The Throfl:le is the fineft of our fong-birds, 
not only for the fweetnefs and variety of it's notes, 
but alfo on account of the long continuance of 
it's harmony; for it favours us with it's fong al- 
moft three parts of the year. 
Like the mifl"el-bird, the Throftle emits it's 
melody from the top of fome high tree; but, in 
order to form it's neft, defcends to fome low 
bufh or thicket: the nefb is cohfirucLed of earth, 
mofs, and firaws; and the infide is curioufly plaif- 
tered v/ith clay. It lays five or fix eggs, of a 
pale blueifh-green colour, marked with duflcy 
fpots. 
Thefe birds are migratory in France: in Bur- 
gundy, they appear juft before the vine-harveil, 
in order to feed on the ripe grapes; and are there- 
fore called la grive de vigne. 
THRUSH; the- Turdus Vifcivorus of Lin- 
nfEus.-" This bird, called alfo the mifiel, is the 
largefb of the genus, weighing nearly five ounces. 
It's length is eleven ir^ehes; and the expanfion of 
it's wings fixteeh and a half. The bill is Ihorter 
and thicker than that of other Thruflhes ; and 
dufky, except at the bafe of the lower mandible^ 
where it is yellow. The head, back, and leffer 
coverts of the wings, are of a deep olive browQ 
hue J 
