Ammonites 
obtusns. 
Atmnonites 
varians. 
ammonio- 
ammonio-. Combining form of ammonium. 
ammonite (am'qn-It), . [< NL. Ammonilis, 
with ref. to the L. name cornu Ammonis, horn of 
Ammon : so called 
from their resem- 
blance to a ram's 
horn: see Am mini 
and -ite 2 .] One of 
the fossil shells of 
an extensive genus 
(Ammonites) of ex- 
tinct cephalopodous 
mollusks (cuttle- 
fishes), of the family 
AiHiiKiiiitida; coiled 
in a plane spiral, and 
chambered within 
like the shell of the 
existing nautilus, to 
wliich the ammon- 
ites were allied. 
These shells have a nacre- 
ous lining and a porcelan- 
ous layer externally, and 
are smooth or rugose, the 
ridges straight, crooked, 
orundulated, and in some 
cases armed with project- 
ing spines or tubercles. 
The species already described number about 500, and range 
from the Lias to the Chalk formations, inclusive. They 
vary in size from mere specks to 3 or 4 feet in diameter. 
Also written hammonitc. Sometimes called snakextone, 
(intiiHtn-gtone, and formerly cornu Aiumonig (Ammon's 
horn). 
Ammonites (am-o-m'tez), n. [NL. : see am- 
monite.] The leading genus of ammonites, 
named in this form by Breyn in 1732, better es- 
tablished by Bruguiere in 1789, giving name to 
the family Ammonitida". The name has lieen used 
with great latitude of definition, but is now much re- 
stricted. Some 40 or more generic names have been given 
to the cephalopods which were formerly referred to Am- 
monites. Also written Hawinonites. See ammonite. 
ammonitid (a-mon'i-tid), n. An ammonite; a 
cephalopod of the family Ammonitida;. 
Ammonitidae (am-o-nit'i-de), n. pi. [NL., < 
Ammonites 4- -ida!.] A numerous family of 
extinct tetrabranchiate cephalopods (cuttle- 
fishes), of which the well-known ammonite is 
the type. Very different limits have been assigned to 
the family. It includes the genera Goniatites, Ceratite's, 
Ammonites, Seaphites, Hamites, and others. They are the 
most characteristic mollusks of the Secondary rocks. See 
ammonite. 
ammpnitiferous (am"6-ni-tif 'e-rus), a. [< am- 
monite + L. ferre = fe. bear^.] Bearing am- 
monites; containing the remains of ammon- 
ites : as, ammonitiferous rocks. 
Ammonitoidea (a-mon-i-toi'de-a), . pi. [NL., 
< Ammonites + -oidea.] A superfamily of tetra- 
branchiate cephalopods, including those which 
have an external shell of two principal layers, 
with an initial smooth chamber and the siphonal 
cavity extending forward. It includes most of 
the order Ammonea. 
ammonium (a-mo'ni-um), n. [NL. (Berzelius, 
1808), < ammonia + -urn.] A name given to 
the hypothetical base (NH 4 ) of ammonia, anal- 
ogous to a metal, as potassium. It has not been 
isolated. If mercury at the negative pole of a galvanic 
battery is placed in contact with a solution of ammonia 
or ammonium chlorid, and the circuit is completed, the 
mass swells to many times its former volume, and an 
amalgam is formed which, at the temperature of 70 or 
80 F., is of the consistence of butter, but at the freezing- 
point is a firm and crystallized mass. This amalgam is 
supposed to be formed by the metallic base ammonium, 
and is the nearest approach to its isolation. On the cessa- 
tion of the current the amalgam decomposes into mercury, 
ammonia, and hydrogen, the two latter escaping as gas in 
the proportions expressed by their atomic weights, namely, 
H and NH^. Ammonium bases, compounds repre- 
senting one or more molecules of ammonium hydrate, in 
which monatomic or polyatomic radicals replace the whole 
or part of the hydrogen, as seen in tetretnyl-ammonium 
iodide, N(C a H B ) 4 I. 
ammoniuret (am-o-ni'u-ret), n. [< ammonia + 
-uret.] In cJiem., one of certain supposed com- 
pounds of ammonia and a pure metal, or an 
oxid of a metal. 
ammoniureted, ammqniuretted (am-6-ni'u- 
ret-ed), a. [< ammoniuret.'] Combined with 
ammonia or ammonium. 
ammonoid (am'o-noid), n. One of the Ammo- 
noidea. 
Ammonoidea (am-o-noi'de-a), n. pi. [NL., < 
Ammonea + -oidea.] An ordinal name ap- 
plied by some authors to the Ammonea. 
Anunophila (a-mof'i-la), . [NL., fern, of am- 
mophitus: see ammophilous.] 1. A small genus 
of grasses growing on the sandy shores of Eu- 
rope and North America ; the sea-reed. A. anm- 
dinacea (common marum, sea-reed, matweed, or sea- 
bent) grows on sandy sea-shores, and is extensively em- 
ployed in Europe and America for preserving the shores 
178 
from inroads of the sea, as it serves to bind down the sand 
by its long matted rhizomes. It is also manufactured into 
door-mats anil Boor-brushes, and in the Hebrides into ropes, 
mats, bags, and hats. 
2. In ciitom., a genus of long-bodied fossorial 
aculeate hymenopterous insects, commonly 
called sand-wasps, 
belonging to the 
family fiphegida:. A. 
liirtijH'Hitix (Walsh) 
is an example. See 
digger-vatp. 
ammophilous (a- 
mof 'i-lus), a. [<NL. 
>i in iHi>/iliil nft, < Or. a/i- 
ftof, sand (see am- 
mite), + <t>i\of, lov- 
ing.] Sand-loving: 
appfied in zoiil. to 
members of the ge- 
nus Ammopliila, 2. 
Ammotrypane (am-o-trip'a-ne), n. [NL., < Gr. 
, sand 
Tainted-wing Digger- or Sand-wasp 
{.trnrnoptiila fittiffnnvt, natural 
size. 
(see ammitt),+ rpi'Travov, borer: see 
trepan.] A genus of cheetopodous annelids, of 
the family Opheliidte. BatJike. 
ammunition (am-u-nish'on), n. [< F. HHiuni- 
tiiin, iimiiniti/iii (16th century), a corruption of 
munition, the prefix n- perhaps arising out of la 
munition understood as Fauiunition : see muni- 
tion.] Military stores or provisions for attack 
or defense ; in modern usage, only the materials 
which are used in the discharge of firearms and 
ordnance of all kinds, as powder, balls, bombs, 
various kinds of shot, etc. Ammunition-bread, 
-shoes, -stockings, etc. . such as are contracted for by the 
government, and distributed to soldiers. Fixed ammu- 
nition, ammunition the materials of which are combined 
in cartridges or otherwise t<> facilitate the loading of fire- 
arms or ordnance. See cartridge. Metallic ammnnl- 
tion, fixed ammunition for small arms, and for machine- 
guns and rapid-firing guns of small raliU-r. inclosed in 
brass or copper cartridge-cases. Stand of ammunition, 
a single charge or load of fixed ammunition for a smooth- 
bore field-piece or other cannon. 
ammunition (am-u-nish'on), i\ t. [< ammuni- 
tion, n.] To supply with ammunition. 
ammunition-chest (am-u-nish'on-chest), n. A 
chest or box in which the fixed ammunition for 
field-cannon is packed. One ammunition-chest is 
carried on the limber of the gun-carriage, and three are 
carried on the caisson, one on the limber and two on the 
body. 
amnemonic (am-ne-mon'ik), . [<Gr. a-priv. 
+ /ivj//iovm6(, mnemonic ; of. ajivrifuw, forgetful. ] 
Not mnemonic ; characterized by loss of mem- 
ory. 
amnesia (am-ne'si-a), . [NL., < Gr. a/ivt/aia, < 
(i-priv. + ftvt/at-, only in comp., remembering, 
< /jtftvi/aicttv, remind, in mid. and pass, remem- 
ber, [ivaoOat, remember, = L. meminisse, remem- 
ber: see mnemonic, memory, remember, etc. Cf. 
amnesty.] 1. In pathol., loss of memory; spe- 
cifically, a morbid condition in which the patient 
is unable to recall a word that is wanted, or, 
perhaps, understand it when spoken: a common 
form of aphasia( which see). 2. [cap.] Imool., 
a genus of coleopterous insects. G. H. Horn, 
1876 Amnesia acustica (see acoustic), loss of mem- 
ory for spoken words ; word-deafness. 
amnesic (am-ne'sik), a. [< amnesia + -ie.] Per- 
taining to or characterized by amnesia or loss 
of memory: as, amnesic aphasia. 
amnestic (am-nes'tik), a. [< Gr. a/tvr/aria, for- 
getfulness: see amnesty and amnesia.] Causing 
amnesia or loss of memory. 
amnesty (am'ues-ti), n. ; pi. amnesties (-tiz). 
[< F. amnestic, < L. amnestia, < Gr. a^vrjnTia, for- 
getfulness, esp. of wrong, < afivr/arof, forgotten, 
forgetful, { o-priv. + fupvyaKetv, /ivdadat, remem- 
ber: see amnesia.'] A forgetting or overlook- 
ing; an act of oblivion; specifically, a general 
pardon or conditional offer of pardon of offenses 
or of a class of offenses against a government, 
or the proclamation of such pardon. 
Dec. 25th, 1868, . . . President Johnson . . . pro- 
claimed and declared ... a full pardon and amnesty . . . 
to all who directly or indirectly participated in the re- 
bellion. Cyc. Polit. Set., I. 90. 
All peace implies amnesty, or oblivion of past subjects 
of dispute, whether the same is expressly mentioned in 
the terms of the treaty, or not. 
Woolsey, Introd. to Inter. Law, 153. 
= Syn. Aluolutimi, etc. See pardon, n. 
amnesty (am'nes-ti), v. t.; pret. and pp. am- 
nestied, ppr. amnestying. [< amnesty, n.] To 
grant an amnesty to ; pardon. 
France has, luckily, little to trouble her beyond the 
question of amnestying the Communists. 
The Nation, XXII. 329. 
The fugitive mauslayer is amnc^tifd, not on the death 
df the king, but on the death of the high priest. 
Enei/f. Brit., XVIII. 510. 
amnion 
amnia. . Plural of amnion. 
amnicH (am'nik), a. [< L. amnicus, < amnis } a 
river, akin to Skt. ap, water.] Of or pertain- 
ing to a river; fluvial; fluviatile. 
amnic- (am'nik), a. [< amnion + -ic.] Same 
as aaiiiiolii'. 
Amnicola (am-nik'o-la), n. [NL., < L. IHI- 
cola, that grows in or by a river, < amnis, a 
river, + -cola, < colere, dwell.] A genus of 
fresh-water tsenioglossate mollusks, of the 
family Kissoida', or made the type of Amnico- 
liltii'. There are several species, of small size, generally 
distributed throughout the United States. 
amnicolid (am-nik'o-lid), . A gastropod of 
the family Aiiniicnliilir. 
Amnicolidae (am-ni-kol'i-de), . pi. [NL., < 
Auniicola + -ida:] A family ,of tssnioglossate 
gastropods, typified by the genus Amnicola. 
The distinction from Itixxnitlir is not well marked, but 
nmiuTous small sjirri.* inhabiting fresh and brackish 
watt T havf been referred to this family. 
Amnicolinae (am-nik-o-li'ne), n. pi. [NL., < 
Amnicola + -ina:] A subfamily of Kissoida>, or 
of Amnicolida;, typified by Amnicola. The animal 
has a fiat foot without lateral sinuses ; the rachidian teeth 
have basal denticles on the anterior surface behind the 
lateral margins ; the shell varies from a turreted to a 
globular 1 1 trin ; and the operculum is subspiral. The sub- 
family includes many small fresh-water species, of which 
a large number inhabit the streams and poolsof the United 
States. 
amnicoline (am-nik'o-lin), a. and n. [< NL. 
nmninilinus, < Amnicola, q. v.] I. a. Inhabit- 
ing rivers, as an amuicolid ; of or pertaining to 
the Amnicolinai; amnicoloid. 
II. n. A gastropod of the subfamily Amnico- 
liini : an amnicolid. 
amnicolistt (am-nik'o-list), n. [< L. amnicola, 
one who dwells by a' river (see Amnicola), + 
-ist.] One who dwells by a river or upon its 
banks. Bailey. 
amnicoloid (am-nik'o-loid), a. [< Amnicola + 
-aid.] Like an amnicolid; pertaining or re- 
lated to the Amnicolida!. 
amnigenoust (am-nij'e-nus), a. [< L. amni- 
gena, born in a river (as fish) or of a river-god. 
< amnis, a river, + -genus, -born, < / "gen, bear.] 
River-born ; born on or near a river. Bailey. 
amnion (am'ni-on), M. ; pi. amnia (-a). [NL.,< 
Gr. apviov, the membrane around the fetus (also 
called ajivelof X"^), a l 80 the bowl in which the 
blood of victims was caught at the sacrifices; 
< afiv6f, a lamb: see agnus.] 1. In anat. and 
vertebrate zool., one of the fetal appendages; 
the innermost one of the membranes which 
envelop the embryo of the higher vertebrates, 
as mammals, birds, and reptiles; the lining 
membrane of a shut sac, familiarly called the 
"bag of waters," in which the fetus is contained. 
An amnion is developed in those vertebrates only which 
have a fully formed allantois ; hence it is absent in the 
Ichthyapsula, or fishes and amphibians, but present in all 
Sauropsida, or reptiles and birds, and in Mammalia. 
The amnion is formed, at a very early period in the life 
of the embryo, by a duplication of the epiblast, or external 
hlastodermic membrane, which, carrying with it a layer 
of mesoblast from the somatopleural division of the latter, 
rises on all sides about the embryo, the folded edges com- 
ing together over the back of the embryo, and there coa- 
lescing to form a shut sac in which the embryo is inclosed. 
From this mode of growth, it is obvious that what was the 
outer side of the amniotic folds becomes the inner side of 
the sac when it has shut, so that the epihlastic layer is in- 
ternal, the mesoblastic external ; the process of inversion 
being comparable to that by which, in the case of the 
primitive trace of the embryo, a layer of epiblast is con- 
verted into the lining of the spinal canal. Only that fold 
of membrane which is next the body of the embryo com- 
poses the amnion prop- 
er, the other or outer 
fold in contact with the 
enveloping primitive 
chorion (vitellme mem- 
brane or yolk-sac)either 
disappearing or taking 
part in the formation of 
the permanent chorion. 
As long as this outer 
fold is recognizable as 
a membrane, it bears 
the name of false am- 
nion. The shut sac of 
the amnion contains the 
liquor amnii, a bland, 
albuminous, serous fluid 
in which the fetus is im- 
mersed. In parturition, 
rupture of the sac is fol- 
lowed by the "bursting 
of the waters." Some- 
times a portion of the 
sac adheres to the head 
VertebrateEmbryo(chick,5thdayof of the child, fitting like 
incubation ), shelving .4,*, the inclosing a skull-cap ; such all ill- 
amnion; n, o, rudiments of antenor , /V ; t v , 
and posterior limbs, or limb-buds; i, fant ls Said 111 the lan- 
2. 3, first, second, and third cerebral guage of mldwives, Who 
vesicles ; la, vesicle of the third ven- commonly Vegard the 
tricle ; h, eye ; *, visceral arches and circumstance as a good 
clefts; All, allantois, hanging by its t i.i uirll with 
pedicle ; Urn. portion o? umbilical omen, to be Ijorn with 
H caul. Those verie- 
