AGO 
ACHALALACTLI. A beautiful American 
bird, remarkable for an annulus or ring of filvery 
whitenefs round it's neck. It is nearly the fize of 
a pigeon ; the beak is fharp, and about three fin- 
gers breadth long ; the head is ornamented with a 
long creft of a blueifh black hue ; the belly, and the 
under-fide of the wings, are white; the back, and 
the exterior part of the wings, like the creft, are of 
a bliieifli black, variegated with white fpots; and die 
tail is partly black, and partly blue. This bird is 
comimonly feen near the lakes and rivers of Mexico, 
where it feeds on fmall fiili, which give it a dif- 
agreeable flavour. 
ACHETA. A name given by the ancient natu- 
raiilts to the large fpecies of cicada; the nymphs 
of which they ufed to eat, and efteemicd them de- 
licious food. 
ACHI^NUS. A term by which the ancients 
denoted a deer or flag in the fecond year of it's age. 
In the firft, they gave it the name of nebrus; in 
the third, it received the appellation of dicrotus ; 
and that of ceraftes was continued ever after. 
ACICUL^. A term ufed by naturalifts to ex- 
prefs thofe fmall fpikes, or prickles,, in the fliape of 
nt edles, with which nature has armed feverai qua- 
drupeds, as well as cruftaceous and teftaceous ani- 
mals. 
ACITLI. Tlie common Mexican name for the 
great-crefted diver, a bird common to Europe and 
America, and more ufually denominated by na- 
turalifts the lepus-aqueus, or water-hare. 
ACO. A name given to a Mediterranean fifli; 
Galled alio aquo, farachus, and farachinus. 
ACOLIN. A bird of the partridge-kind com- 
mon in Cuba and Hifpaniola. It is about the fize 
of a ftarling; it's legs and feet are of a pale green- 
ifh colour; it's toes are very long; it's breaft and 
belly are white; it's beak is yellow, and longifh; 
it's head is fmall ; it's fides are fpotted with brown ; 
and it's back and tail are of a duflvy yellowifh 
brown. The tail is very fhort; and both that and 
the back have fome black fpots, with narrow 
bars of white. This bird frequents the margins of 
lakes, where it is fuppofed to feed on flies, worms, 
and other infefts ufually produced in a watery 
foil. It is killed for it's fiefli, and is eiteemed 
very agreeable food. 
ACONTI AS . A fpecies of ferpent, called alfo 
jaculum, or the dart-fnake, from the manner in 
which it vibrates it's body. It's motion is the 
Iwifteft of any known reptile, and is performed by 
coiling itfelf upon it's tail, and darting to it's full 
extent; then, carrying it's tail, as quick as lightning, 
to the head, coiling and darting again. In this 
manner it proceeds with extreme rapidity, without 
ever quitting the ground. It has been generally 
believed that this ferpent poiTeffes the faculty of 
flying; and, indeed, it is frequently known to dart 
down from trees on it's prey : but, if we confider 
the length and weaknefs of this animal, and the pe- 
culiar conformation of the vertebrjE, in which all the 
junctures are form.ed to give motion, and none to 
give power, we cannot conceive by what means it 
can attain the faculty of fpringing from the ground. 
It is found in Egypt, L.ybia, and the Mediterra- 
nean iflands. It's length is about three feet; it's 
colour is a milky grey on the back, variegated 
with fmall black fpots, appearing like lb many 
eyes ; and it's belly is perfeftly white. The neck 
is wholly black, and from that two milk-white 
ftreams run all along the back to the tail ; and tiie 
black fpots are each furrounded with a circle of 
white. 
ACT 
ACORN. A genus of fliells, called lepas and' 
balani by Linnaeus, of which naturalifts enumerate 
only afew fpecies, or families. The Acorn-fhell is 
multivalvular, unequal, and fixed by a ftem, or 
felTil; the valves lie parallel to each other, and in 
a perpendicular pofition, contrary to that of all 
other valves, which lie horizontally. The in- 
clofed animal performs it's necefTary funftions by 
an aperture at the top; for the valves, being defti- 
tute of hinges, never open orfeparate. It affixes 
itfelf to other bodies by the bottom, and is never 
found detached from fome folid body, fuch as 
larger fnells and ftones. 
The Britifh coafts furnifta fix different fpecies of 
Acorns,, which tlie ingenious Mr. Pennant diftin- 
guiflies by the names of the common, fulcated, 
Cornifti, ftriated, bell, and anatiferous Acorns ; fo 
called from the variations in their colour and con- 
formation. 
The tentacula from this animal being feathered, 
; our creduious anceftors, both naturalifts and hif- 
, torians, conceived the idea that it gave origin to a 
bird called the barnacle-goofe. So long did this 
, opinion prevail, that we find, in the Philofophical 
: Tranfa6tions of this country, a grave account of it's 
; transformation into a bird ; which gave the late Dr. 
Hill an opportunity, in his difpute with the Royal 
Society, of expofing die credulity of that refpefta- 
ble body, and their too great love of the marvel- 
lous. As it may be amufing to infpeil the philo- 
fophy of our progenitors, we fhall tranfcribe the 
following ridiculous account from Gerard. 
; " What our eyes have feen, and hands touchedj,. 
we fhall declare. There is a linall ifland in Lan- 
cafhire, called the Pile of Foulders, wherein are 
found the broken pieces of old and bruifed fliips^^ 
feme whereof have been caft thither by fhipwreck; 
and alfo the trunks and bodies, with the branches, 
i of old and rotten trees, caft up there likewiie; 
whereon is found a certain Ipume, or froth, tliat int 
time breedeth unto certain fnells, in fhapelikc 
f hofe of the mufcle, but fharper pointed, and of a 
whitifft colour ; v/herein is contained a thing in form 
like a lace of filk, finely woven, as it were, toge- 
ther, of a whitifh colour; one end whereof is fa- 
ftened unto the infide of the fliell, even as the fifli 
of oyfters and mufcles are; the other end is made 
faft unto the belly of a rude mafs, or lump, which in 
time cometh to the fhape and form of a bird.- 
When it is perfeitly formed, the ftiell gapeth open,: 
and the firft thing that appeareth is the lace or' 
ftring ; next come the legs of the bird hano-ino- 
out; and, as it groweth greater, it openeth the 
fhell by degrees, till at length it is all come forth, 
and hangeth only by the bill : in fliort^fpace af- 
; ter it cometh to full maturity, and falleth into 
the fea, v/here it gathereth feathers, and groweth 
to a fowl bigger tlian a mallard, and lefTer than a 
goofe ; having black legs, and bill or beak, and fea- 
thers black and white, fpotted in ftich m.anner a& 
is our magpye, called in fome places a pie-annetj^ 
which the people of Lancafhire call by no other 
name than a tree-goofe; vv^hich place aforefaid,-- 
and all thofe parts adjoining, do fo much abound^ 
therewith, that one of the beft is bought for three- 
pence. For tiie truth hereof, if any doubt, may ic 
pleale them to repair unto me,, and I fliall fatisfy' 
them by the teftimony of good witnefTes.' 
ACTINIA. A genus of fes-animals of die 
order of the gymnarthria, naturally of a cylindric 
fliape, but of a variable figure : the tentacula are 
very numerous^ and arranged in feverai feries round 
the 
