A C B 
A C H 
which he imputes to milk-meats turning ftale and 
four. The feat of thefe infefls is chiefly in the 
hands and feet, though they are fometimes found 
in the arms and legs. 
ACARUS is alfo ufed by naturalifts as a claffi- 
cal name of the lice of anim.als, whofe genera are 
almoft as numerous as the animals on which they 
breed. In the Linnaean fyftem it is a genus of ap- 
tera, with eight legs, two eyes at the fides of the 
head, and two jointed tentacula, comprehending 
thirty-five fpecies, of which the following are the 
moft remarkable. 
Acarus with very long legs, called by Mou- 
fet the long-legged fpider, and by Ray and others 
the afh-coloured crefted fpider. 
Acarus with nippers like crabs, has the fore- 
legs formed like thofe of a crab or fcorpion, for 
which reafon it is by fome called the fcorpion fpi- 
der. This infeft has a roundifli inflated body of 
a whitifli colour, covered with a thin fmooth fl^.in ; 
the head is fmall, and of a dufl<y hue towards the 
mouth. It is frequently found in old rotten wood. 
Acarus with very long fore-feet, is about the 
fize of a nit. The body is long, and of a wax- 
colour, the legs being pale. It is found chiefly 
on champignons. 
Acarus with the fecond pair of legs very thick, 
is always feen on the ground, particularly in gar- 
dens, it is armed with four exceeding fmall teeth ^ 
it's fize is inferior to that of a loufe ; and it's colour 
is a dull chefnut. 
Acarus with the third pair of feet largefl:, by 
fome called the bird flea, from it's being found on 
that tribe of animals. 
AcaRis red, v/ith the fore-feet longefl:, and the 
hind part of the belly forked, is remarkable for hav- 
ing two fmall horns near the lower belly. 
Acarus, with a livid belly of a fallow colour, oval 
before and with feelers like clubs, by fome natural- 
ifts is called the dog-loufe, and is known by a black 
round fpot near the bafe of the lower body. The 
bre^ft is fcarcely perceptible; the head is fmall and 
black; the mouth is forked; and the feet are black. 
Acarus deprelTed, afh-coloured, with rough 
fides, is a very fmall infcft, which appears in the 
beginning of fpring, but at other times retires into 
the earth. 
Acarus with a depreflTed belly, by fome called 
the red little water-fpider, lives entirely on the 
water, is often feen on lakes, and runs with great 
velocity. 
Acarus with a depreflfed belly, by Ray called the 
red fmall earth-fpider, is found only in the earth. 
Acarus red, with fides of a darker colour, is a 
very common infecft, living upon trees, and remark- 
able for it's fwiftnefs. 
Thefe are the mofl: confiderable Acari ; but fo 
numerous are their tribes, and fo widely are they 
diflTeminated through animate and inanimate ob- 
jefts, that neither the naturalift can enumerate them, 
nor the naked eye behold them. Myriads fvs^arm 
around, imperceptible to us: they float in our 
drink; overfpread our food and fruits ; and, if con- 
tinually viewed with a microfcopic eye, would 
make us loath the choicefl: viands, abjure the ne6la- 
reouscup, and naufeate the moft delicious produc- 
tions of nature. Even thofe infeils which we call 
Acari, have likewife their Acari, endued with life 
and motion, and capable of enjoyments fuited to 
their refpeftive fpheres of aftion. 
r ACBAB. A bird of the Philippine iflands, ge- 
nerally found in a wild ftate, and very mucli re- 
fembling our common hen. It feeds on rice and 
other vegetables ; but, being fhort-winded, and in- 
capable of taking long flights, is eafily caught. It 
is reckoned wholefome food, and is therefore often 
deftroyed. 
ACCIPENSER. In the Linnaean fyfcem, a 
genus of fifii, of the order of nantes, and clafs of 
amphibia. The diftinguifhing characleriftics of 
this genus are, that the mouth is retraftile, and 
deftitute of teeth ; and the gills have only one hole 
or aperture on each fide. 
Of this genus there are only three fpecies: the 
fturgeon, the Accipenfer ruthenus, and the hufo 
or ifinglafs-fifh. 
A variety of difputes have originated among 
naturalifts, whether the fturio or fturgeon be the 
fame fifli with the Accipenfer; and what con- 
ftituted the difference between the A^ccipenfer and 
the filurus of the ancients : but the relult of the 
whole appears to be no more than this, that the 
Romans gave the name of Accipenfer to the ftur- 
geon which was caught in their own feas, and ufed 
frefh; and called that filurus which was imported 
in pickle from the coafts of Greece. 
ACCIPITER. The name of a whole order of _ 
birds, the general chara6leriftic of which is their 
having a hooked or aduncated beak. Of this or- 
der there are four genera; the vultur, falco, ftrix, 
and lanius; and feventy-eight different fpecies. 
See Vulture, Owl, Falcon, and Hawk. 
ACCIPITER. A name given by Gellius and 
other ancient writers to the fifli ufually called mil- 
vus and lucerna. Artedi diftinguifhes it by the 
name of trigia with the head a little acculcated, 
and a fingular fin placed near thofe of the peftoral. 
ACEPHALOUS. A term given to fuch ani- 
mals as are either deftitute, or fuppofed to be defti- 
tute, of heads. Tlius the lumbricus latus, or joint- 
worm, was long imagined to be Acephalous; but 
Tulpius, and after him Fehr, difcovered that it 
did not pofiefs this uncommon property ; the for- 
mer, indeed, making it biceps, or two-Iieaded. 
The ancient naturalifts, at the head of whom is Pliny, 
amufed themfelves with notions of Acephalous 
men and women, as well as Acephalous animals; 
but whether they applied the term by way of far- 
cafm, or really thought fuch people exifted, remains 
unknown. Certain it is, that though by fome 
aberration of nature there may have been Ace- 
phalous individuals, there never was, nor could be, 
a whole nation which pofiefifed this fingularity. 
ACERINA. A name given by Pliny, and the 
old naturalifts, to the fifh called in modern tinies 
ceruna, and aurata fluviatilis; in Englifti, the 
ruffe. This is unqueftionably a genuine fpecies 
of perch, and is diftinguifhed from other flfh of that 
genus by having the dorfal fin fingle and the head 
cavernous, 
ACHAC. A Philippine bird, about the fize of 
a common hen. The belly, breaft, and neck, are 
of a pale brown, and the back is of a duflcy reddifti 
hue : the wings are principally compofed of blueifli 
green feathers of extraordinary beauty; the tail is 
white, fliort, and continually in motion ; the eyes 
are black; the beak is of a thick, ftrong, obtufe 
figure, tinged with black; the legs are reddifli, 
and the claws are black. This bird, which is pro- 
perly of the partridge kind, lives chiefly about the 
cultivated parts of the Philippine iflands, feeding 
on rice and other vegetables; and, when difturbed, 
feems to repeat the word 'Phi! Phi!' without 
intermiffion. 
C ACHA- 
