Mesocarpaceae 
families of algse into which the group Conju- 
gate is divided. The sexual reproduction is by a pro- 
cess of conjugation, which may be either scalariform (that 
is, between two or several cells of two different filaments) 
or lateral (that is, between two adjacent cells of the same 
filament). The result of this conjugation is the produc- 
tion of a globular zygosperm, which differs from that pro- 
duced by the Zygnemacece in that immediately after its 
formation it divides into two, three, or more cells, the cen- 
tral one only of which is fertile. Sometimes Mcsocarpineae. 
Mesocarpus (mes-o-kar'pus), n. [NL. (Has- 
sall, 1845), < Gr. /ti'aof, middle, + Kaptro;, fruit.] 
A genus of fresh-water algse, typical of the fam- 
ily Mesocarpacece. The copulation is scalariform, and 
the spores are spherical or oval, between two cylindrical, 
straight, or slightly inbent cells. 
mesocephalic (mes-o-se-fal'ik or -sef 'a-lik), a. 
[< Gr. fteaof, middle, + /ce^a/li?, head, + -io.~] 1. 
In craniom., of medium size ; neither large nor 
small ; with a capacity of from 1,350 to 1,450 
cubic centimeters. 
A. skull of variable form, mostly nwsocephalie. 
W. H. Flower, Pop. Sci. Mo., XXVIII. 317. 
2. Having a skull of medium breadth or ca- 
pacity. 
mesocephalism (mes-o-sef 'a-lizm), n. [< tneso- 
cephal-ic + -ism.'] The character or state of 
being mesocephalic. Also mesocephaly. 
Departures from a width of eight and length of ten 
(mesocephalism), measured from one auricular aperture 
over the head to the other, and nose root over the head to 
the nucha, determine whether the skull shall be consid- 
ered long. Amer. Nat., XXII. 614. 
mesoceplialon (mes-o-sef 'a-lon) ; n.; pi. 
cephala (-lit). [NL.,< Gr. /itirof, middle, + ite 
head.] Same as mesencephalon. 
mesocephalous (mes-o-sef'a-lus), a. [< Gr. 
/isaof, middle, + Ksifta^, head, + -CMS.] Meso- 
cephalic. 
mesocephaly (mes-o-sef 'a-li), n. Same as meso- 
cephalism. 
mesochil (mes'o-kil), n. [< NL. mesochilium, 
q. v.] Same as mesochilium. 
mesochilium (mes-o-kiri-um), n. [NL., < Gr. 
/ito-of, middle, + ^Xof, lip.] The intermedi- 
ate part of the lip of such orchids as have this 
organ separated into three distinct parts. Lind- 
ley, Treasury of Botany. 
mesochoros (me-sok'o-ros), n. [< Gr. /ica6xopof, 
standing in mid-chorus, < /isaof, middle, + xP^, 
chorus.] Same as coryphceus, 1. 
mesoccele (mes'o-sel), n. Same as mesocwlia. 
mesocoelia (mes'-o-se'li-a), n. ; pi. mesoccelice 
(-e). [NL., < Gtr.'/tcaof, middle, + noMa, a hol- 
low, ventricle : see ccelia.~] The ventricle of 
the mesencephalon ; the mesencephalic cavity 
of the brain, connecting the diacoelia with the 
epicoelia; the aqueduct of Sylvius. B. G. 
Wilder. 
mesoccelian (mes-o-se'li-au), a. [< mesoccelia 
+ -an.~\ Of or pertaining to the mesocoalia of 
the brain. 
Mesocoele tubular ; mesocaelian roof quadrilobate. 
Amer. Nat., XXI. 914. 
mesocolic (mes- o -kol ' ik), a. [< mesocolon + 
-ic.] Of or pertaining to the mesocolon : as, 
a mesocolic peritoneal fold; mesocolic attach- 
ment. 
mesocolon (me-sok'o-lon), n. [NL., < Gr. 
[icaoKohov, less prop, [leaoitukov, the part of the 
mesentery next the colon, < psaof, middle, + 
K&Xov, the colon: see co?ow 2 .] The mesentery 
of the colon; the peritoneal fold which holds 
the colon in place. 
mesocpracoid (mes-o-kor'a-koid), a. and n. [< 
Gr. /j.iaos, middle, +' E. cdracoid.] I. a. Situ- 
ated between the hypercoracoid and the hypo- 
coracoid. 
II. n. An element in the shoulder-girdle of 
teleost fishes, disintegrated from the coracoid 
or paraglenal cartilage, and intermediate be- 
tween or bridging over the hypercoracoid and 
hypocoracoid. It is developed in the malacop- 
terygian and plectospondylous fishes, but is 
lost in the acanthopterygiaus. 
mesocuneiform (mes-o-ku'ne-i-f6rm), n. and a. 
[< Gr. [ttaof, middle, +' E. cuneiform.'] I. n. In 
anat. and zool., the middle one of the three cu- 
neiform bones of the tarsus, lying between the 
ectocuneiform and the entocuneiform. It is in 
special relation with the head of the second 
metatarsal bone. Also called mesosphenoid. 
II. a. Middle, as a cuneiform bone ; pertain- 
ing to the mesocuneiform. 
mesode (mes'od), n. [< Gr. [ieau<S6c, a mesode 
(see (let), < /jsaof, middle, + addeiv, pdeiv, sing, 
> y&ii, a song, ode: see ode.] In fine, pros., a 
system of metrically different composition in- 
3724 
tervening between a strophe and its antis- 
trophe. See epode. 
mesoderm (mes'o-derm), n. [< Gr. fteaot;, mid- 
dle, + depfia, skin.] 1. The middle germinal 
layer of the three-layered embryo of any meta- 
zoic animal, lying between the endoderm and 
the ectoderm. The term is used synonymously with 
mesoWast, the correlation being endoderm, mesoderm, 
and ectoderm ; hypoblast, mesoblast, and epiblast ; or mu- 
cous, vascular, and serous layers. Most of the body of 
every metazoan animal is derived from the mesoderm. 
When the embryo becomes four-layered, as it usually does, 
this state results from the splitting of the mesoderm into 
an inner visceral and an outer parietal layer, called respec- 
tively splanchnopleural and somatopleural, or involuntoma- 
t&ry and voluntonwtory. 
2. In bot., the middle layer of tissue in the shell 
of the spore-case of an urn-moss. 
mesodermal (mes'o-der-mal), a. [< mesoderm 
+ -al."\ Of or pertaining to the mesoderm in 
plants or animals; having a middle germinal 
layer. 
Mesodermalia (mes"o-der-ma'li-a), n.pl. [NL., 
< Gr. ptaof, middle, 4- Kpfia, skin.] Spongio- 
zoa or Porifera regarded as a prime division 
of the grade Ccelentera, whose archenteron is 
a branching canal-system communicating with 
the outer water by a set of inhalent and exha- 
lent pores ; the sponges : opposed to Epithela- 
ria, or all other coalenterates collectively. K. 
von Lendenfeld. 
mesodermalian (mes"o-der-ma'li-an), a. and 
n. [< Mesodermalia + -an.'] I. a. Pertaining to 
the Mesodermalia, or having their characters. 
II. n. A member of the Mesodermalia. 
mesodermic (mes-o-der'mik), a. [< mesoderm 
+ -ic.] Pertaining to or of the nature of a meso- 
derm or middle germinating layer; mesoder- 
mal. 
And so form the foundation of the nwsodermic invest- 
ment by which the body cavity of the adult is lined. 
A. Sedgwidc, Micros. Science, XXVII. 499. 
Mesodesma (mes-o-des'ma), n. [NL., < Gr. 
/zfo-of, middle, + fieafia, a 
band: see desma.~\ A ge- 
nus of wedge-shells of the 
family Donacidai, or made 
type of a family Meso- 
desmida;, having a thick 
solid trigonal shell with 
two short stout lateral 
teeth, and the cartilage 
internal. Species abound 
in the Australian region. 
Mesodesmidse (mes-o-des'mi-de), n.pl. [NL., 
< Mesodesma + 
-idee. ] A family 
of bivalve mol- 
lusks, named 
from the genus 
Mesodesma. J. 
E. Gray, 1840. 
mesodic (me- 
sod'ik), a. [< 
mesode + -ic."] 
In anc. pros., constituting or pertaining to a co- 
lon, line, or system of a different length or metri- 
cal character interposed between two cola, two 
sets of uniform lines, or two systems of iden- 
tical metrical form; especially, constituting, 
pertaining to, or containing a system of differ- 
ent form intervening between a strophe and 
its antistrophe. See epodic, palinodic, periodic, 
proodic. 
mesodont (mes'o-dont), a. [< Gr. fieaof, mid- 
dle, + 6<5oi>f (bSovr-) = E. tooth."] 1. Inanthro- 
pol., having medium-sized teeth: as, the meso- 
dont races. 2. In zool., pertaining to the Meso- 
donta, or having their characters. 
Mesodonta (mes-o-don'ta), n. pi. [NL., < Gr. 
fitaog, middle, + bSoix; (6<Wr-) = E. tooth."] A 
group of extinct mammals of North America, 
resembling Insectivora, characterized by Cope 
as a suborder of Bunotheria, having the incisors 
not growing from persistent pulps, the molars 
tubercular and never sectorial, the third tro- 
chanter apparently elevated, and the astragalus 
not grooved above. Ten Eocene genera are re- 
ferred to this group. 
mesoduodenal (mes-o-du-o-de'nal), a. [< meso- 
duodenum + -al.~] Of or pertaining to the meso- 
duodenum. 
mesoduodemim (mes-o-dii-o-de'num),. [NL., 
< Gr. titcos, middle, + NL. duodenum, q. v.] 
The fold of peritoneum which incloses and sup- 
ports the duodenum; the duodenal mesen- 
tery. 
mesogaster (mes-o-gas'ter), H. [NL., < Gr. 
middle, + facri/p, belly.] 1. An inter- 
Mesodesma glabratum 
right valve. 
Donacilla chiltnsis, one of the Meso- 
desmidte right valve. 
mesolabe 
mediate part of the intestine, extending from 
the pylorus to the csecum, and including the 
small intestine with its annexes, as the liver 
and pancreas, also, in the fetus, the umbilical 
vesicle. It is commonly called the mid-yut. 
2. [cap."] A genus of fossil fishes. Agassiz. 
mesogastral (mes-o-gas'tral), a. [^mesogaster 
+ -a/.] Of or pertaining to the mesogaster. 
mesogastric (mes-o-gas'trik), a. [< mesogas- 
trium + -ic."\ 1. Of or pertaining to the meso- 
gastrium; umbilical, as a region of the abdo- 
men ; mesenteric with reference to the stomach 
or to the mesogaster. 2. In Crustacea, situ- 
ated in the middle of the gastric lobe of the 
carapace : specifically applied to a median sub- 
division of that lobe, the mesogastric lobe. See 
cut under Brachyura. 
mesogastrium (mes-o-gas'tri-um), n. [NL., < 
Gr. juraof, middle, + yaar^p, belly.] 1. In hu- 
man anat., the umbilical region of the abdomen, 
between the epigastrium above and the hypo- 
gastrium or epipubic region below. See cut 
under abdomen. 2. In anat. and goal., the mes- 
entery of the stomach ; the fold of peritoneum 
which holds the stomach in place. It is a portion 
of the common intestinal mesentery, in early fetal life in- 
distinguishable therefrom, but afterward variously modi- 
fled. 
mesogenous (me-soj'e-nus), a. [< Gr. /Arof, 
middle, + --yevr/f, born, produced: see -genous.] 
Increasing by growth at or from the middle, as 
the spores of certain fungi. [Rare.] 
mesoglcea (mes-o-gle'a), n. [NL., < Gr. /thof, 
middle, + -fkola, y'Aoia, glue : see glue."] 1. The 
mesodermal intercellular substance, or ground- 
substance, of some animals, as sponges and 
other coslenterates. B. von Lendenfeld, Proc. 
Zool. Soc., London, 1886, p. 566. 2. [cap."] A 
genus of gelatinous seaweeds, typical of the 
Mesoglwacea!, with olive-brown branching fili- 
form fronds. The unilocular sporangia are oval in 
shape and borne at the base of peripheral filaments ; the 
plurilocular sporangia are unknown. Agardh, 1817. 
Mesoglceaceae (mes"o-gle-a'se-e), n. pi. [NL. 
(Kuetzing, 1843), < Mesoglcea + -acea?.] A fam- 
ily of olive-green seaweeds with a gelatinous or 
cartilaginous thallus of hemispherical or cylin- 
drical outline, forming small gelatinous or slimy 
cushions or branching tufts on other larger sea- 
weeds : the same or nearly the same as the 
Chordariea; or Chordariacea of Harvey. See 
Chordariece. 
mesogloeal (mes-o-gle'al), a. [< mesoglcea 4 
-a.] Consisting of, pertaining to, or resem- 
bling mesogloaa. 
mesoglutseus (mes"o-glo-te'us), n. ; pi. mesoglu- 
tcei (-5). [NL.,< Gr. picas, middle,-!- NL. glutcevs, 
q. v.] The middle gluteal muscle ; the gluteeus 
medius. 
mesogluteal (mes l! 'o-glo-te / al), a. [< mesoglu- 
tceus + -a.] Of or pertaining to the mesoglu- 
tseus. | 
mesognathic (mes-og-nath'ik), a. Same as 
mesognathous. 
mesognathous (me-sog'na-thus), a. [< Gr. 
/icaof, middle, + yvdBo;, jaw.] 1. Having a 
moderate or intermediate gnathic index of from 
98 to 103, as a skull. 2. Having a skull thus 
characterized, as a person. 
mesognathy (me-sog'na-thi), n . [As mesognath- 
ous T -y."] That character of a skull or person 
in which the jaws are moderately prominent 
anteriorly, indicated by a gnathic index of 
from 98 to 103. 
Mesohippus (mes-o-hip'us), n. [NL., < Gr. 
fitaog, middle, + jirn-of, a horse.] A genus of 
very small three-toed horses, of the family 
Equidce, founded by Marsh in 1875 upon remains 
from the early Miocene of North America. The 
animal was only about as large as a sheep, with three func- 
tional digits on each foot, and an additional splint-bone on 
each of the fore feet. 
mesolabe (mes'o-lab), n. [< L. mesolaJnum, < Gr. 
"/jsao^dfliov, prop. /Ja62.a/3ov, fiea6^af)of, an in- 
strument invented by Eratosthenes for finding 
mean proportional lines, < peaof, middle, mean 
(neut. pi. fiiaa, mean terms), + Za/i()dviv, y ?,a/3, 
take. Of. astrolaoe."] A mechanical contrivance 
for geometrically extracting the roots of quan- 
tities. It consists of a number of equal rectangles, each 
haying a diagonal marked, and all capable of sliding along 
a line common to the bases of all, so that they partially 
overlap one another. The marked diagonals are all par- 
allel. To use the instrument, all the intersections, each 
formed of the diagonal of one rectangle and the overlap- 
ping edge of the next one, are brought, by the sliding 
along of the rectangles, into one straight line with one ex- 
tremity of the diagonal of the uppermost rectangle and a 
point on the exposed edge of the lowermost whose distance 
from the extremity of the diagonal on the same edge mea- 
sures the quantity whose root is to be extracted. Then 
