tetrabranch 
longing to tlie '/"< inilimiirliiiitu. or having their 
characters. 
II. a. A cephalopod of the order Tetriilinni- 
fliintii, MS mi ammonite or a pearly nautilus. 
Tetrabranchiata (tet-ra-bnmg-ki-ii'tii), . i>i. 
[NL., neut. pi. of tftriihrnnchiatun: sec ti'trn- 
braneliiittc.JAii 
mx 1 ten ,, 
tr 
cJi 
8fi 
Pearly Nautilus (M 
.'. funnel ; At, shell-muscle : >' \ . 
ntle ; br, br.inchi.e ; gn, nlda- 
' 
(.'. hood 
mental gland ; r, r' , position of ren;il appen- 
dages ; tint*, horny rinp ; <n\ ovary ; fal, ovl- 
duc.il gland ; sfh , siphuncle ; ftt, black^part 
of shell under mantle ; 
cartilaginous skeleton i 
, process of the 
to the funnel. 
order (if <'i-/il{<i- 
III/HII/II, named 
by Owen from 
the two pairs of 
gill-plumes, or 
I'teiiidiul bran- 
i-liin'. Theneph- 
riitla arc also two 
pairs ; two visceri- 
cardiac oriflces 
open upon the ex- 
terior; and the ovi- 
ilii.-ls and >]i< i m 
ducts are [min-ii. 
hut the left is ru- 
dimentary. There 
are many sheathed 
clrcumoral tenta- 
cles, not lieltriliK 
suckers, two hol- 
low eyes, two ol- 
factory organs, no 
ink-hag, and a 
large many-cham- 
bered shell, straight or coiled. The order has Included 
both ammonold and nautilold forms, but has also been 
restricted to the latter. They abounded In former times, 
aft is shown by the immense number and variety of fos- 
sils, hut are now nearly extinct, being represented by the 
pearly nautilus only. See also cut under nautilui. 
tetrabranchiate (tet-ra-brang'ki-at), n. and . 
[< NL. tetriilirinicliiatus, < Gr. rcrpa-, four, + 
ftp&YXia, gil's.] Same as tetrabranch. 
tetracamarous (tet-ra-kam'a-rus), a. [< Gr. 
rfrpa-, four, + Ka/iapa, a vault.] In hot., hav- 
ing four closed carpels. 
tetracarpellary (tet-ra-kftr'pe-la-ri), a. [< Gr. 
rrrpa-, four, -I- NL. carpellum, carpel, + -ary.] 
In hot., having four carpels. 
Tetracaulodon (tet-ra-ka'lo-don), n. [NL. 
(Godman), < Gr. rerpa", four, + ratvidf, stem, + 
bfol'f, tooth.] A genus of mastodons. See 
Mastodontinae. 
Tetracera (te-tras'e-rji), n. [NL. (Linneeus, 
1737), so called from' the four horn-like carpels 
of the original species; < Gr. rrrpa-, four, + x/pac, 
horn.] A genus of polypetalous plants, of the 
order Dilleiiinfex and tribe Delinieie. It is charac- 
terized by flowers in terminal panicles, each usually with 
five spreading sepals, as many petals, numerous stamens, 
and three to five acuminate carpels, usually shining, coria- 
ceous, and follicular in fruit, and containing one to five 
seeds surrounded by a lacerate aril. There are about 36 
species, widely scattered through the tropics. They are 
shrubby climbers, or rarely trees, smooth or rough-hairy, 
with parallel feather-veined leaves and the panicles most- 
ly yellow and loosely many-flowered. Several species are 
sometimes cultivated as greenhouse climbers ; several are 
used as astringents, as the decoction of T. oblonyata In 
Brazil, and In Cayenne the infusion of T. Tiijarea, the 
tigarea, or red creeper. T. aln^fotia, the water-tree of 
Sierra Leone, is so named from the clear water obtained 
by cutting its climbing stems. 
Tetraceras (tc-tras'e-ras), . [NL. (Hamilton 
Smith, 1827), also fetraceros, Tetraccrus, < Gr. 
Terpantpuf, four-honied, < rrrpa-, four, + nfpac, 
horn.] A genus of four-horned Borida, as T. 
quadricornis, an Indian antelope. The female 
is hornless. See cut under niriiir-deer. 
Tetracerata (tet-ra-ser'a-tft), n. pi. [NL., pi. of 
"tetraccrtis: see fetraceras.] One of two fami- 
lies of De Blainville's (1825) poly branchiate 
Paracephalophom, consisting of various gen- 
era, not all of which were properly grouped to- 
gether. They are mostly nudibranchiate or notobran- 
chiate gastropods. The family is contrasted with Vice- 
rota. Also Tetracera. 
tetracerous (te-tras'e-rus), n. [< Or. - 
put, four-horned, < reran-, four, + xepat, horn.] 
In conch., having four horns or feelers, as a 
snail. 
Tetracha (tet'ra-ka), n. [NL. (Hope, 1838), < 
Gr. rirpax , in. four parts, < TCT/XJ-, four.] A 
notable genus of tiger-beetles, of the family ( '/- 
cimli li<l;c. comprising about 50 species, mainly 
South American and West Indian, a few. how- 
ever, inhabiting Australia, North America, 
southern Europe, and northern Africa. They have 
the hind coxee contiguous, the eyes large and prominent, 
and the third joint of the maxillary palpi longer than the 
fourth. T. carolitKi and T. virffinuxt, two large handsome 
metallic beetles, are found in the 1'nited States; the latter 
is crepuscular, and both are noted enemies of certain in- 
jurious larva;. See cut under tiger-beetle. 
tetrachaenium (tet-ra-ke'ni-um), n. ; pi. tftni- 
rlnniiii (-ii). [Also ti-triii-hiiiiinn: < Gr. rerpa-, 
four, + xairetv. open.] In hot., a fruit formed 
by the separating of a single ovary into four 
nuts, us in the l.liinta>. Ili-nslmr. [Hare.] 
MM 
Tetrachaetae (tet-ra-ke'te>, . pi. [NL.. pi. of 
ti-triii-li.rtii* : see ti tnn-li.-rt'iiix.] A division of 
br.ichycoron.s IHjili-ni. containing those tlie* 
which' are tetraehjetous: correlated with l>i- 
i-lnrlii- and lit .rni'lurta. 
tetrachastous (tet-ra-ke'ttis), a. [< Gr. rerpa-, 
four. + xa'ini, mane : see clueta.] Having the 
haustellum composed of four (not of t wo or six) 
pieces, as n fly; of or pertaining to that divi- 
sion of brachycerous dipterous insects whose 
haustellum is of this character: correlated w ith 
itirlifl'tniis and liexaclisetoun. See cuts under .\i/c- 
I>IIIIK and Afili'fi/i. 
tetrachiru8(tet-ra-ki'ru). n.;T>\.tetrachiri(-ri). 
[NL., < Gr. n ru&xetp, four-handed, < rerpa-. four, 
-T- xf'p, hand.] In teratol., a monster with four 
hands. 
tetrachord (tet'ra-k6rd), n. [= F. tetracorde, 
< Gr. nrpaxopoof, having four strings, < rerpa-, 
four, + xopSI], a string, chord : see chord.'] In 
mimic: (a) An instrument with four strings. 
(6) The interval of a perfect fourth, (c) A dia- 
tonic series of four tones, the first and last of 
which are separated by a perfect fourth. The 
tetrachord was the unit of analysis in ancient music, like 
the hexachord In early medieval music, or the octave in 
modern music. It Is asserted that originally the term was 
applied to a series consisting of a given tone, its octave, 
its fourth, and a tone a fourth below the octave (as, 
1,1;, A, I'-); but in its usual form ft was a diatonic series. 
Three varieties were recognized, differing in the position 
of the semitone. The Dorian tetrachord had the semi- 
tone at the bottom, the Phrygian in the middle, and the 
Lydian at the top, thus : 
Dorian, ~ * 
Phrygian, * 
Lydian, - * - * w 
Of these the Dorian was regarded as the chief or standard. 
Scales were made up by adding tetrachords together. 
When successive tetrachords had a tone In common, they 
were called conjunct; when they were separated by a 
whole step, ili*juHct (thus, E-A, A-D would represent 
the former, and E-A, B-E' the latter). Octave-scales 
were made up of two disjunct tetrachords, the separating 
interval being called the diazeuctic tone. (See rmxfri , 7 (a).) 
'I In- completed system of tones finally adopted by the 
Greeks embraced a total compass of two octaves, extend- 
ing upward from a tone probably nearly equivalent to the 
second A below middle C, as tones are now named. The 
various tones of this system were distributed among five 
tetrachords, and named accordingly, as follows : 
I Extreme. 
Distinct , 
J a b e d 
^* 
' Conjunct. 1 Middle. 1 Lowest. 
'f TY |* r r r , EEEE 
S2 ! m J 
hi j k I tn n o p q 
mt 
r 
a, nete hyperbpla-on ; <*, paranete hyperbolaeon ; t, trite hyperU> 
l.r-nii ; d, nete diezeugmenon ; r, patanete diezeugmenon ; /, trite 
diezeuffmetion ; g, paramese ; h, nete syneinmenon ; I, paianete sy- 
Ttenimenon ; ; . trite synemmeoon ; i, tnese ; /, lichanos mcsun ; m, par- 
hypate meson ; n, hypate meson ; e, lichanos hypatcn ; /, parhypate 
hypaton ; g, hypate nypaton ; r, proslambanomenos. The terms tty- 
pcrbotmon, ditMtMfmrHett, syntmmerttm, mesa*, and hyfaton are 
really genitives plural, but are sometimes loosely used as names of 
the tetrachords. 
It should further be noted that the Greeks recognized two 
other varieties of tetrachords the chromatic, consisting 
of two semitones and a minor third, and the enharmonic, 
consisting of two quarter-tones and a major third. The 
tetrachord is more or less recognized in modern music, 
the major scale being conceived of as made up of two dis- 
junct Lydian tetrachords, and the minor scale of two dis- 
junct tetrachords, the lower Phrygian, and the upper 
either Dorian (In the descending minor) or Lydian (in the 
ascending). 
tetrachordal (tet'ra-k6r-dal), a. [< tetrachord 
+ -a/.] In music, pertaining to a tetrachord, 
or consisting of tetrachords: as, the tetraclionlti/ 
musical theory of the Greeks Tetrachordal 
system, a name applied to one of the early forms of the 
tonic sol-fa system of teaching music. 
tetrachordon (tet-ra-k6r'don), w. [NL.: see 
tetrachord."} A musical instrument in which, 
while it has strings and a keyboard, like the 
pianoforte, the tones are produced from the 
strings by pressing them, by means of the digi- 
tals, against a revolving cylinder of india-rub- 
ber covered with rosin. Compare liarmonichord, 
hurdy-gurdy, and keyed riolin (under keyed). 
tetrachotomous (tet-ra-kot'o-mus), a. [< Gr. 
rtrpaxa, in four parts (<! rer/ia'-, four), + -ro/iof, < 
rffivetv, rafifiv, cut.] In :oi>l. and hot., doubly 
dichotomous; arranged in four ranks or rows"; 
iinadrifarious; divided into four parts, or into 
sets of four; quadripartite. 
tetrachronous (te-trak'ro-nus), a. [< Or. rt- 
rpaxpovof, of four times, < rerpa-, four, + xp> n f, 
time.] In anc. pros., having a magnitude of four 
primary or fundamental times: tetraseinir. 
tetracladine (tet-ra-klad'in), a. [<Gr. myz-, 
four, + E. <-/<idi>ie.~\ Cladose, or branching into 
Tetradecapoda 
a number of variously shaped processes, as a 
caltrop or sponge-picnle of the tetraxon type. 
/;,--/.-. lini.. XXI I. 417. 
tetracladose (tet-ra-kla'dos), a. [< Gr. rcrpa-, 
four. + 10. i-lniliini .} Same as tetracladine. 
tetracoccous (tet-ra-ke.k'un), n. [< Gr. rerpa-, 
four, + MMA<, berry.] In lot., having four 
cocci or carpels. See cut under coccus. 
tetracolic (tet-ra-ko'lik), n. [< tetracol(mi) + 
-if.] In anc. proa., consisting of four cola or 
series. 
tetracolon (tet-ra-ko'lon), M.; pi. tetracola (-IB). 
[LL., < Qr.reTpaKu'Aov, neut. of TerpaitMor.,<. nrfta-, 
four, + KU'/JW, a limb, a member: see eotonl.] In 
inn: rlict. and pros., a period consisting of four 
cola. 
Tetracoralla (tct'ra-ko-ral'ft), . pi. [NL., < 
Gr. rerpa-, four, + lOpiMiav, coral.] A division 
of corals, corresponding to the Rugosa. 
tetracoralline (tet-ra-kor'a-lin), a. [< Tetra- 
coralla + -iwr'.] Of or pertaining to the Tetra- 
i-nnillii: rugose, as a stone-coral. See Cyathtix- 
innillte. 
tetract(tet'rakt), a. [< Gr. Ttrpa-, four,+ axrif, 
a ray, beam.] Having four rays, as a sponge- 
spicule; quadriradiate. See cut under sponge- 
./lirtllc. 
tetractinal (te-trak'ti-nal), a. [< tetractine + 
-a/.] Having four rays, as a sponge-spicule. 
tetractine (te-trak'tin), a. [As tetract + -tne 1 .] 
Having four rays, or being quadriradiate, as a 
sponge-spicule. 
tetractinellid (t-trak-ti-nel'id), a. and . I. 
a. Pertaining to the Tetractinellida, or having 
their characters. 
II. n. A member of the Tetractinellida. 
Tetractinellida (te-trak-ti-nel'i-dft), n. pi. 
[NL., < Gr. rerpa-, four, + a*r<f (OKTIV-), ray, + 
-ella + -i<la : see tetract.] In Spllas's classifica- 
tion of sponges, the second tribe of Silicifpon- 
yiie, contrasted with Monaxonida, including 
those Demospongix which possess qnadriradi- 
ate or tritene spicules or lithistid scleres. It 
includes the great majority of existing sponges, and is 
divided into Choristiila and Lit/Mida. 
tetractinellidan (te-trak-ti-nel'i-dan), a. [< 
TetractincJIida + -an.] Same as tetractinellid. 
tetractinelline (te-trak-ti-nel'in), a. [< Te- 
Irni'tinill(iiln) + -ine 1 .] Same as tetractinellid. 
tetractomy (te-trak'to-mi), . [Properly "tet- 
rachotomy (of. dichotomy, tetrachotomoutt), < Gr. 
Ttrpaxa, in four parts, + -rofiia, a cutting, < ri/t- 
vttv, Tafieiv, cut.] A division into four parts. 
The one key to St. Paul's meaning is the principle that, 
besides body and soul which make up man's natural be- 
ing regenerated man possesses spirit, the principle of 
supernatural life. This has been somewhat unfairly called 
Bull's theory, and accused of making up a Utractomy 
body, soul, spirit, and Holy Spirit. 
Speaker s Commentary, 1 Thes. v. 23. 
tetracyclic (tet-ra-sik'lik), a. [< Gr. rtrpa-, 
four, T a-fic/of, ring.] In bot., having four cir- 
cles or whorls of floral organs : said of flowers. 
tetrad (tet'rad), n. [< Gr. rerpac, (-a<5-), the 
number four, < rerpa-, four: see tetra-.'} 1. The 
number four; also, a collection of four things. 
Also quadrad. 2. In chem.,nn atom the equiv- 
alence of which is four, or an element one atom 
of which is equivalent, in saturating power, to 
four atoms of hydrogen. 3. In morphology, a 
quaternary unit of organization resulting from 
individuation or integration of an aggregate of 
triads. See triad, iluad. 
tetradactyl. tetradactyle (tet-ra-dak'til), o. 
and M. [ ' Gr. re TpadaicTv/jor, , having four fingers 
or toes, < rerpa-, four, + <5dcTvtaf , a finger, toe : 
see dactyl.] I. a. Having four fingers or toes; 
quadridigitate : noting either (o) the fore feet 
or the hind feet of a quadruped, or (6) a four- 
toed bird, or (c) a quadruped only (when four- 
toed before and behind). 
II. n. A four-toed animal. 
tetradactylity (tet'ra-dak-til'i-ti), M. [< tetra- 
ilnct\jl + -iti/.] Tetradactyl character or state. 
\titiire, XLIII. 329. 
tetradactylous (tet-ra-dak'ti-lus), a. [< tetra- 
dactyl + -OM.] Same as tetradactyl. 
tetrad-deme (tet'rad-dem), w. A colony or 
aggregate of undifferentiated tetrads. See 
triad-ileme, dyad-dcme. Encyc. Brit., XVI. 843. 
tetradecapod (tet-ra-dek'a-pod), a. and n. [< 
Gr. rtrpa-, four. + Aena, ten, + JTOI'Y (irof!-) = E. 
foot.] I. a. Having fourteen feet; of or per- 
taining to the Trtritdrrunoda. 
II. . A member of the Tetradecapoda. 
Tetradecapoda (tet'ra-de-kap'6-d&), . ///. 
[NL.: see MrwiMqpodJ Fourteen-footed crus- 
taceans; an order of I'rnslacra corresponding 
