626 II Y D 
one flower, which- is white, and of very Ihort duration, 
fel'dom continuing above three or four hours after it is 
expanded. The fruit is red ahd fucculent; a compound 
berry like the rafpberry and mulberry. Native of Canada. 
It was cultivated in 1759, by Mr. Miller; and flowers in 
May and June. This plant, not increafing much, is 
rather uncommon in the Englifh gardens; it delights 
in great fhade and moifture; and when planted in dry 
ground, or much expofed to the fun, it rarely lives 
through one fummer. In a moift loamy foil and lhady 
fituation, if it be left undilturbed three or four years, 
it will flourilh. 
fIYDRAU'LICS,yi The fcience of the motion of fluids, 
and the conftruction of all kinds- of inftruments and 
machines relating thereto. See the article Mechanics. 
HYDRAU 7 LUS,y; water, and a.v\og, Gr. a pipe.] 
An organ played by the motion of water. 
HYDRENTEROCE'LE,/ [c&. p , Gr. water, eflepon, an 
inteftine, and v.iy-n, a tumour.] A dropfy of the fcrotum. 
Vogel defcribes this diforder as compounded of a dropfy 
and hernia. 
HYfDRIA, or Idria, a town of Germany in the duchy 
of Carrtiola: nine miles fcuth-fouth-weft of Crainburg, 
and 154 fouth-fouth-weft of Vienna. Lat. 46. 12. N. ion. 
31.44 E. Ferro. 
HY'DRIA, a river of Germany, which rifes near Ge- 
welb, pafles by the town of Hydria, and runs into the 
Lifonzo, in the duchy of Carniola. 
HYDROCE'LEjyi [t/Jlvp, Gr. water, and xrfa, a tu¬ 
mour.] The droply in the fcrotum. See the article Pa¬ 
thology. 
HYDROCEPH'ALUS,/ [vSw, Gr. water, and xitpuXn, 
the head.] A dropfy in the head. 
HYDROCERATOPHYL'LUM,/ in botany. See Ce- 
RATOPHYLLUM. 
HYDROCH'ARIS,yi [from v$a<g, Gr. water, and %api?, 
grace; the grace or beauty of the water.] In botany, 
the Frog-Bit ; a genus of the clafs dioecia, order ennean- 
dria, natural order of palm®, (hydrocharides, JuJf.) The 
generic characters’ are—I. Male. Calyx: fpathe three- 
flowered, two-leaved, oblong. Perianthium: proper, 
three-leaved; leaflets ovate-oblong, concave, membra¬ 
naceous at the edge. Corolla: petals three, roundilh, flat, 
large. Stamina: filaments nine, awl-Ihaped, upright, in 
three rows, the middle one puts forth an awd-fhaped ftipe 
from the inner bale, like a ftyle, which is placed in the 
centre; the two others are connected at the bafe, fo that 
each inner filament coheres with each outer. Antherae 
Ample. Piltillum: the rudiment of a germ in the centre. 
II. Female. Calyx: fpathe none; flowers folitary. Pe¬ 
rianthium, as in the male, fuperior. Corolla, as in the 
male. Piltillum: germ roundilh, inferior; llyles fix, the 
length of the calyx, comprelfed, bifid-channelled ; ltigmas 
bifid,acuminate. Pericarpium: capfulecoriaceous, round¬ 
ilh, fix-celled, feeds numerous, very final!, roundilh.— Ef- 
fential CharaEler . Male. Spathe two-leaved ; calyx trifid ; 
corolla three-petalied ; filaments the three inner ftyle-bear- 
ing. Female. Calyx trifid ; corolla three-petalled ; Ityles 
fix; capfule fix-celled, many-feeded, inferior. 
Hydrocharis morfus ran®, or frog-bit: a Angle fpecies. 
It has a root of many long thick white fibres; leaves at 
each joint of the ftalk, fix or eight together, floating, 
roundilh, kidney-lhaped, flelhy, fmooth, thick, perfectly 
entire, almoll tranfparent, reddilh underneath, marked 
with a few circular and many tranfverfe veins; they are 
about an inch and a half in diameter, and, when dry, on 
removing the outer Ikin, a molt beautiful dole net-work 
of veins is feen. Leaf-ftalks from three to fix or feven 
inches long, round, fmooth, thick, transparent, having 
numerous crofs bars. Sheaths in plants of both fexes 
numerous, next the foot, ovate, tranfparent; in the male 
plant there is alfo a pair about the middle of the flower- 
' Stalk, containing the tender unopened blolfoms as in a 
bladder. Flower-ftalks the fame length with the leaf- 
ftalks, upright; in the male producing three or’ four 
II Y D 
flowers, in the female only one; corolla white, with a. 
yellow bottom, a little wrinkled and tender; calyx yel- 
lowilli. This• plant increafes by’runners, furnilbed with 
pendulous gems, fupported on long foot-ftalks. Thefe 
gems confift of two itipulaceous fcales, folded together, 
within which are curioufly enveloped the embryo leaves 
of the future plant. Native of many parts of Europe, in 
deep ditches, and flow ftreams, with a muddy bottom, 
multiplying itfelf greatly by runners which fiioot out to 
a gre?.t length, and at the joints drop down long roots, 
which penetrate deep into the mud. It flowers from June 
through the autumn. Ray found a variety, with a 
double flower fmelling very fweet, in a ditch by the fide 
of Audrey-caufeway, clofe by the great wooden bridge, in 
the ifle .of E’iv, plentifully. 
HYDROCOT'YLE, f. [from tX ? , Gr. water, and 
kotvAij, a finall cavity, veifel, or cup ; becauie it grows 
in water, and the leaves are hollow; or the leaves, being 
hollow, contain water.] Water Navelwort, Marsh 
Pennywort, or Sheep’s-eane ; in botany, a genus of 
the cials pentandria, order digynia, natural order of uni- 
cellat® or umbellifer®. The generic characters are— 
Calyx: umbel Ample; involucre commonly four-leaved, 
finall. Pertanthium fcarcelyany. Corolla: univerfid uni¬ 
form in figure, not in fituation ; florets all fertile; pro¬ 
per, five-petalled ; petals ovate, acute, fpreading, entire. 
Stamina: filaments five, awl-lhaped, fhorter than the co¬ 
rolla; anther® very finall. Piltillum: germ upright, cora- 
p relied, orbiculate, inferior, peltate; Ityles two, awl-fhaped, 
very fliort; ltigmas Ample. Pericarpium none; fruit or- 
biculate, comprelfed, tranfverfely bipartite. Seeds two, 
femi-orbiculate, comprelfed.— EJJential CharaEler. Umbel 
Ample, with a four-leaved involucre; petals entire; feeds 
femiorbiculate-comprelfed. 
Species. 1. Hydrocotyle- vulgaris, common marlh pen¬ 
nywort, or Iheep’s-bane: leaves peltate, crenate, umbeFs 
five-flowered. Roots perennial, capillary, whitilh. Stems 
creeping, round, fmooth, Itriking root at the joints. 
Leaves orbicular, fmooth, glofly, bright green, about an 
inch in diameter, waved, fcalloped or forriewhat lobed 
and notched on the edge, the centre a little deprefled, 
and marked with a white dot; the veins form a kind of 
net-work on both furfaces; leaf-ftalks about two inches 
long, upright, round, fmooth, naked below, above befet 
with briftly, horizontal, diftant, hairs. Seeds of a pale 
brown colour. Linn®us remarks, that this plant has a 
Ample umbel proliferous from the centre, and the two 
ftyles diftant. Native of molt parts of Euro fie in marfties ; 
alfo in Japan and Jamaica ; but not common. It flowers 
with us from May or June through July and Augufi. 
The flowers, being very finall, and hidden by the leaves, 
are not much remarked, though they are abundant’in 
their feafon; but the plant is eafily known by the petiole 
of the leaf being inferted into the middle of it, a circum- 
ftance uncommon in European plants. 
Gerarde calls this plant water penny-woort, Jkcep-killing 
penny-grajfe, penny-rot-, in the north country, he fays, it is 
called wkite-rot, to diftinguifli it from the drolera, or red- 
rot ; in Norfolk jlowkwoort (from its being fuppofed to oc- 
cafion the flukes in the liver of rotten lheep); and by the 
hulbandmen Jheep's-bane, becaufe it killeth lheep that do 
eat thereof. This however is now known to be a vulgar 
error; for the rot in lheep is owing to an inteftinal worm, 
which we know could never be generated by vegetable 
food even of the ranked kind. See the article Fasciola:, 
vol. vii. p. 267, and the correfpondenE Engraving for a 
correft figure of the fluke-worm. See alfo the article Hel¬ 
minthology, Plate II. fig. 19. vol.ix. p. 348, 349. This 
plant, (Hydrocotyle vulgaris,) together with Drofera, or 
fundew, and Pinguicula, or butterwort, is very common 
in marlhy places, and therefore the diforder has been af- 
cribed to thefe; though it is pretty certain that neither 
lheep nor any other quadruped feed on thefe plants. 
That fheep-farmers, however, may be acquainted with 
tills plant, we have given an exaft reprefentation of it at 
