hydroxid 
more hydroxyl groups : as, potassium Ttydrostd, 
KOH; ethyl hydroxid, C 2 H 5 OH. Hydroxids may 
be regarded as formed from water (HOH), by the substi- 
tution for one of its hydrogen atoms of a metal or basic 
radical. An acid radical combined with hydroxyl is called 
an acid, the term hitdroxid being reserved for basic com- 
pounds. Also spelled hydroxyd, hydroxyde. 
hydroxyl (hi-drok'sil), n. [< ltydr(oqen) + 
ox(ygen) + -yl.] A compound radical (OH) 
which has never been isolated, but which is a 
factor in avast number of chemical compounds. 
Thus, the oxygen bases are regarded as compounds of hy- 
droxyl with electropositive atoms or radicals, as sodium 
hydroxid, XaoH. The oxygen acids are also regarded as 
compounds of hydroxyl with electronegative atoms or radi- 
cals, as sulphuric acid, SCWOHfe. Water may be regarded 
as hydroxyl hydrid, HOH. 
hydrozinkite (hi-dro-zing'kit), n. [< Gr. Map 
(i'dp-), water, + E. zi>tkite.~] A hydrous zinc 
carbonate occurring in massive earthy forms 
of a white or nearly white color. 
Hydrozoa (hi-dro-zo'a), u. pi. [NL., pi. of hy- 
drozoon, q. v.] A class of Ccelenterata, one of 
two prime divisions of that subkingdom, Acti- 
nozoa being the other. The Hydrozoa are aquatic 
and chiefly marine organisms, single or oftener compound, 
and nearly always soft and gelatinous (in some cases with 
a chitiuous perisarc). Each individual polypite consists 
Diagrams of Principal Forms of the Ifydrt 
relations. 
IV 
oa in their mutual 
i, hydra ; a, sertularian ; 3, calycophoran ; 4, physophoridan ; 5, 
lucernarian. I, II, III, IV, successive stages of a medusiform gono- 
phore, or medusoid. In any figure : a, ectoderm ; *, endoderm ; 
c, digestive and somatic cavity ; A, air-vesicle ; A\ hydrophyllium ; 
C, hydrotheca ; F, pneumatophore ; G, gonophore ; N, nectocalyx ; 
P, tentaculum ; ., hydranth ; T, ccenosarc. 
essentially of a simple sac composed of an outer (ectoder- 
mal) and an inner (endodermal) membrane, with a simple 
gastrovascular cavity or stomach-sac, not differentiated 
into an esophageal tube nor separated from the general 
body-cavity, developed as an outward process of the body- 
wall, and usually furnished with tentacular processes. 
The reproductive organs are external to the body. Repro- 
duction is accomplished either by sexual elements (ova 
and spermatozoa) or by gemmation or fission ; the genera- 
tive zooids are developed as mednsoid organisms, which 
may become detached and free-swimming, or remain per- 
manently attached to the parent stock. The class is of 
world-wide distribution, and includes the numerous crea- 
tures known as hydroidx, acalephx, medusans, jelly-fish, sea- 
blubbers, etc. Their forms are endlessly varied, and range 
in complexity from the simple fresh-water hydra to the 
complicated structure of the oceanic hydroids, as the Por- 
tuguese man-of-war. The classification of the Hydrozoa 
varies with different writers, and it is difficult to define 
most of the larger groups into which they have been di- 
vided. They are separated into from three to six groups, 
as the Hydrophora, Discophora, and Siphoiwphora of Hux- 
ley's arrangement, or the Hydroida, Siphonophora, Lu- 
cernarida, Dixcophora, Graptolitidte, and Hydrocorallince 
of Nicholson's arrangement. The class is sometimes call- 
ed Polypomedusce. It was named as a class of Polypi by 
Owen in 1843. 
hydrozoal (hi-dro-zo'al), a. [< hydrozoon + 
-al.~\ Pertaining' to or resembling the Hydro- 
zoa; hydrozoan. 
The theca of hydrozoal polypes. Huxley. 
hydrozoan (hl-dro-xo'an), a. and . [< hydro- 
zoon + -an.'] I. 'a. Pertaining to the Hydro- 
zoa; resembling the Hydrozoa, or having their 
characters. 
II. n. One of the Hydrozoa, as an acaleph, 
medusan, or jelly-fish. 
hydrozoic (hl-dro-zo'ik), a. [< hydrozoon + 
-ic.~\ Of the nature of Hydrosoa; hydrozoan. 
As a question of development, the formation of the radi- 
ate Echinoderm within its vermiform larva seems to me to 
be analogous to the formation of a radiate Medusa upon a 
Hydrozow stock. Huxley, Critiques and Addresses, p. 282. 
hydrozoon (hl-dro-zo'on), . ; pi. In/drozoa (-a). 
[NL., < Gr. vfiup (vtip-), water, + C<? 01 '> an ani- 
mal: see <>6>ii'.] A hydrozoan. 
2941 
Hydrurese (hl-dro're-e), n. pi. [NL. (Mene- 
ghini, 1838), < Hydrurus + -co, 1 .] A division 
of fresh-water alg, of the order Cor.eopliyce<e, 
typified by the genus Hi/drums. This division 
is no longer accepted, the genera being now re- 
ferred to the tribe Palintillacew. 
hydrurett (hi'di-Q-ret), n. [< liydr(oijen) + 
-ret.] Same as hydrid 1 . 
hydrurla (hi-dro'ri-a), . [< Gr. Map (v6p-), 
water, + ovpov, urine.] \Tipathtil., an excessive 
flow of watery urine. 
Hydrurus (hi-di'6'rus), n. [NL. (Agardh, 1824), 
< Gr. iifiup (v6p-), water, + o'ipd, a tail.] A ge- 
nus of fresh-water algas, of the order Coccophy- 
cece, tribe Palmellacea;. The thallus, which is from 2 
to 12 inches long, is adnate, gelatinous, more or less firm, 
variously divided, and sticky ; the cells are at first globose 
or subglobose, afterward elongated or elliptic, and ar- 
ranged more or less regularly in longitudinal families; 
propagation is by means of agile gonidia. In a fresh state 
some of the species have a very offensive odor. By some 
algologists the species of Hydrurus are referred to the 
geuus Cluzella. 
Hydrus (hi'drus), n. [NL., < Gr. Mpoc, a water- 
snake: see hydra.'} 1. A southern constellation 
introduced in the sixteenth century. It lies 
south of Eridanus, Horologium, and Reticulum, 
and contains three stars of the third magni- 
tude. 2. A genus of venomous sea-snakes, 
type of a family Hydridai: now disused, the 
genus being termed Hydropliis, and the family 
Hydrophidce. Schneider, 1799. 3. [1. c.~\ Some 
fabulous or undetermined water-snake. 
Cerastes horn'd, hydrus, and elops drear. 
Milton, P. L., x. 525. 
hyeit.t'.andw. An obsolete form of Me. Chaucer. 
hye 2 t, An obsolete form of high. 
hyemalt, a. An improper form of hiemal. 
hyematet, hyemationt. Obsolete forms of JW- 
emate, hiemation. 
hyent, hyenet, [< ME. hyene, < OF. hyene, F. 
hyene, < L. liycma : see hyena.] Obsolete forms 
of hyena. 
The nedith not the galle of no hyene 
That cureth eyen derked for penaunce. 
Chaucer, Fortune, 1. 35. 
I will laugh like a hyen, and that when thou art inclined 
to sleep. Shak., As you Like it, iv. 1. 
hyena (hi-e'na), n. [Formerly hyen, hyene, q. v. ; 
= F. hyene = Pr. hiena, yenna, iana = Sp. hiena 
= Pg. hyena = It.jena = D. hyena = G. hyane = 
Dan. hywne = Sw. hyena, < L. hyatna, < Gr. ixuva, 
a hyena, so called from its bristly mane, like a 
hog's, < if, a hog (= L. sus = E. sow), + fern. 
term. -cn>a.] 1. A carnivorous quadruped of 
the genus Hyaena or family Hyamidoe. There are 
several kinds of hyenas. The common striped or laughing 
hyena, Canis hutena or Hy&na etriata, known to the an- 
cients as a wild beast of Libya, has long been celebrated 
for the great size and strength of its neck and Jaws, its for- 
midable teeth, its prowling nocturnal habits, its -singular 
voice, and its propensity for robbing graves. It has a wide 
geographical distribution, including most of Africa and 
much of Asia, as Syria, Mesopotamia, Persia, and India. 
It is an unsightly animal of ferocious aspect, of the size of 
a large dog, with shaggy pelage bristling over the shoul- 
ders, a short bushy tail, large eyes and ears, thick blunt 
muzzle, and peculiar carriage, due to the low hind quar- 
ters, high shoulders, and long heavy neck. Its feet are 
digitigrade, with blunt non-retractile claws. Its color is 
brownish-gray, more or less distinctly and extensively 
banded or striped crosswise with black oil the back, 
sides, and limbs. The animal is nocturnal, hiding by day 
in caves, and hunting by night in packs for its food, 
which is chiefly carrion, though it often preys upon liv- 
ing animals. It is not less cowardly than ravenous, but 
is capable of being tamed and even domesticated. The 
brown hyena, H. brunnea, inhabits southern Africa; it 
belongs to the same restricted geuus as the striped hyena, 
but is mostly of a dark-brown color, banded only on the 
limbs, and the pelage is remarkably long and shaggy, 
growing to a length of 8 or 10 inches on the back and 
sides. The spotted hyena, B. crocuta or Crocuta macula- 
Hygeian 
And scorning all the taming arts of man, 
The keen hyena, fellest of the fell. 
Thomson, Summer, L 921. 
2. The pouched dog, the thylacine dasyure of 
Tasmania, Thylacinus cynocephalus : so called 
from its predaceous and carnivorous habits. 
See zebra-wolf. 
Also spelled hyama. 
hyena-dog (hl-e'na-dog), n. 1. The aardwolf. 
See I'roteles. W. Nwainson. 2. The hunting- 
dog, or painted hyena, Lycaon pictus, a large 
spotted wild dog of Africa, resembling a hyena 
in some superficial respects. It is, however, a 
true dog, of the subfamily Caninte. J. E. Gray. 
hyenet, . See hyen. 
hyenic (hi-en'ik), a. [< hyena + -ic.~\ Like a 
hyena ; having the character of a hyena. Also 
spelled hyamic. 
The Arabs . . . call certain men hyaenic, and believe 
that there is an irresistible affinity between them and the 
hyaina. W. R. Smith, Kinship and Marriage, p. 208. 
hyeniform (hl-en'i-f6rm), . [< NL. hyami- 
f/>rmis, < L. hycena, a hyena, + forma, form.] 
Having the character of a hyena or of the 
Hyatnida:; pertaining to the Hyceniformia. Also 
spelled hyceniform. 
hyenine (hi-e'nin), a. [< hyena + -tne 1 .] Having 
the character of a hyena ; pertaining to or char- 
acteristic of the Hyamido!; hyeniform. Also 
spelled liyamine, 
The hyenine habit of walking or crawling upon wrist 
and ankle-joints when fighting or defending itself, with 
the object of defending its feet from injury. 
Stand. Sat. Hist., III. 435. 
hyenoid (hi-e'noid), a. [< Gr. vaiva, hyena, + 
cidof, form.] Hyena-like ; hyeniform ; hyenine. 
Also spelled hyammd. 
hyetal (hi'e-tal), a. [< Gr. ver6f (= Umbrian 
savitu), rain, { veiv, send rain ; vei, it rains, = 
Zend ^ hu = Skt.'v/stt, express juice (see sowa).] 
Of or relating to rain, or its distribution with 
reference to different regions ; descriptive of 
the rainfall of different districts; pluvial; rainy. 
hyetograph (hi'e-to-graf), n. [< Gr. ircrof, rain, 
T ypaQetv, write.] A chart showing the average 
rainfall of the earth or of any of its divisions. 
hyetographic (lu'e-to-grafik), a. [< hyetogra- 
phy + -z'c.] Pertaining to hyetography. 
hyetographical (hi"e-to-graf'i-kal), a. [< hye- 
tographic + -al.'] Same as hyetographic. 
Such [rain-]maps are generally called Hyetographical 
or Hyetological maps. Huxley, Physiography, p. 46. 
Spotted Hyena (Hyttna crocuta or Crocuta macula/a). 
ta, is a more distinct species, generically different from 
either of the foregoing, inhabiting southern parts of Afri- 
ca. As its name implies, it is spotted instead of striped ; 
and it is rather smaller than //. vtriata, and has a less shag- 
gy pelage. In this species the length of the neck, size of 
the head, shortness of the loins, and lowness of the hind 
quarters are specially notable. The cave-hyena, H. spe- 
Itvux, is an extinct form closely related to the spotted hy- 
ena ; its remains occur in caverns. There are also other 
fossils to which the name hyena has been applied, and the 
hyena-dog is culled painted hyna. 
hyetography (hl-e-tog'ra-fi) , . [< Gr. feroV, rain , 
+ -ypatyia. < ypcujieiv, write.] The art of show- 
ing the distribution of rain; that branch of 
meteorology which ascertains and exhibits in 
charts, etc., the rainfall of different localities 
in a given time. 
hyetological (hi"e-to-loj'i-kal), a. [< hyetology 
T -ie-al.] Of or pertaining to hyetology. 
hyetology (hi-e-tol'o-ji), . [< Gr. fcrdf, rain, 
+ -Aoy/a, < teyeiv, speak: see -ology.~\ That 
branch of meteorology which treats of the phe- 
nomena of rain. 
hyetometer (hl-e-tom'e-ter), n. [< Gr. iierof, 
rain, + /icrpov, a measure.] A rain-gage. 
hyetometrograph (hi"e-to-met'ro-graf), n. [< 
Gr. ifroc, ram, T /terpov, a measure^ + ypatyeiv, 
write.] A rain-gage which automatically regis- 
ters the amount of rainfall and the time of its 
occurrence. 
In Hermann's hyetometrograph, 1789, a fixed funnel con- 
ducts the rain into one of twelve glasses placed on the 
circumference of a horizontal wheel, which is turned by 
clockwork, so that each glass remains under the funnel 
for one hour. Encyc. Brit., XX. 257. 
Hyetornis (hi-e-t6r'nis), . [NL., < Gr. ver6(, 
rain, + opvtf, a bird.] A genus of American 
cuckoos, of the family Cucidida, based upon the 
rain-bird of Jamaica, H. plnvianus. P. L. Scla- 
ter, 1862. Also called Hyetoniantis. Cabanis, 
1862. 
Hygeia (hi-je'a), . [The usual form given to L. 
Hygea or Hygia, strictly *Hygiea or, after the 
Gr. spelling (of the diphthong), *Hygieia, < Gr. 
'Ty/cio, the goddess of health, a personification of 
iiy/ejo^health, soundness of body,< vyais, healthy, 
sound: of. Skt. ugra, formidable.] 1. In clas- 
sical myth., the goddess of health, the chief of 
the daughters of ^Esculapius (Asklepios). She 
is represented as a maiden, fully draped, and usually hold- 
ing a patera. She frequently has also the long staff or scep- 
ter, another attribute of her father, and is commonly ac- 
companied by the jEsculapian serpent, which may belooked 
upon as an embodiment of the delegated healing power 
of Apollo. 
2. The 10th planetoid, discovered by De Gas- 
paris, at Naples, in 1849. 
Hygeian (hi-je'an), a. [< Gr. vyietn., health 
(see Hygeia), + -an.] 1. Eelating to Hygeia, 
