V E C 
though of different appearances ; and this 
whether the matter is disposed of in one or 
two, or in 20 crusts, laid regularly round a 
nucleus; or thrown irregularly, without a 
nucleus, into irregular lines; or, lastly, if 
blended into an uniform mass. 
These are the three states in which every 
pebble is found ; for if it has been naturally 
ynd regularly formed by incrustation round 
a certain nucleus, we laid that always the 
same in the same species, and the crusts not 
FED 
The peet ens, such as the sole pccten, the 
ducal-mantlie pccten, the knotted, and others/ 
seem to be in general inhabitants of the In- 
dian seas ; some of them frequent those of 
Africa, and the South seas. The most re- 
markable species is the maximus or great 
scallop, being the same with what Barbut 
calls the ducal-mantle pecten. It lias fourteen 
rays, very prominent and broad, and striated 
both above and below. They are rugged, 
and imbricated with scales. 1 hey grow to 
FED 
5 67 
jess regular and certain. If the whole has a large size, are found in beck by themselves, 
been more hastily formed, and the result 
only of one simple concretion, if that has 
happened while its different substances were 
all moist and thin, they have blended toge- 
ther and made a mixed mass of the joint co- 
lour of them all. But if they have been 
something harder when this has happened, 
and too far concreted to diffuse wholly 
among one another, they are found thrown 
together into irregular veins. These are the 
natural differences of all the pebbles ; and 
having regard to these in their several varie- 
gations, all the known pebbles may be re- 
duced to 34 species. 
Such pebbles as are found in strata near 
the surface of the earth, are much more 
brittle than those which lie in deeper strata ; 
and the more clear and transparent the sand 
is which is found among pebbles, the more 
beautiful the pebbles are generally observed 
to be. 
PENCHBLENDE, one-of the ores of 
uranium. See Uranium. 
PEC OB A, in zoology, the fifth order of 
the class mammalia, in the Linnsan system : 
they are thus distinguished ; fore-teeth up- 
per', none ; lower, cutting, many ; feet hoof- 
- ed, cloven; food herbs, which they pluck; 
chew the cud; stomachs four; the paunch 
to macerate and ruminate the food ; the bon- 
net, reticulate, to receive it; the omasus, or 
maniples of numerous folds, to digest it; and 
the abomasus or caille, fasciate, to give it 
aceseency, and prevent putrefaction. In 
this order there are eight genera, viz. the 
antelope, bos, Camelopardalis, camelus, 
capra, cervus, moschus, and ovis. 
PECTEN, the scallop ; a genus of shell- 
fish, the characters of which are these : the 
animal is a tethys ; the shell bivalve and un- 
equal ; the hinge toothless, having a small 
ovated hollow. 1 his shell-fish is one of the 
spinners, having the power of spinning 
threads like the muscles ; but they are much 
shorter and coarser than even those of that 
fish, so that they can never be wrought 
into any kind of’work like the longer and 
finer threads of the pinna marina. The use 
of the threads which are spun by the scallop 
is, to fix the creature to any so! id body near 
its shell. All these proceed, as m the 
muscle, from one common trunk. -It is an 
evident proof that the fish has a power of 
fixing itself at pleasure to any solid body by 
means of these threads, that after storms the 
scallops are often found tossed upon rocks, 
where there were none the day before ; and 
yet these are fixed by their threads, as well 
as those which had remained ever so long- 
in their place. They form their threads in 
the very same manner with the muscle ; only 
their organ which serves for spinning is short- 
er, and has a wider hollow, whence the 
threads are necessarily thicker and shorter. 
11 
aiw 'Hedged up, and barrelled for sale. The 
antienu say that they have a power of re- 
moving themselves from place to place by 
vast springs or leaps. This fish was used 
both by the Greeks and Latins as a food. 
When dressed with pepper and cummin, it 
was taken medicinally. The scallop was 
commonly worn by pilgrims on their hat, or 
the cape of their coat, as a mark that they 
had crossed the sea in their way to the Holy 
Land, or some distant object ot devotion. 
PEC US, a genus of the class and order 
-syngenesia polygamia superflua. The cal. 
is five-leaved, cylindric; florets in the ray 
five ; down awned ; recept. naked. There 
are four species, annuals of the West Indies. 
PECULIAR, in the canon law, signifies a 
particular parish or church that has jurisdic- 
tion within itself for granting probates of 
wills, and administrations, exempt from the 
ordinary or bishop’s courts. The king’s 
chapel is a royal peculiar, exempt from all 
spiritual jurisdiction, and reserved to the 
visitation and immediate government of the 
king himself. There is likewise the arch- 
bishop’s peculiar ; for it is an antient privi- 
lege of the see of Canterbury, that wherever 
any manors or advowsons belong to it, they 
forthwith become exempt from the ordinary, 
and are reputed peculiars ; there are fifty - 
seven such peculiars in the see of Canter- 
bury. Besides these, there are some pe- 
culiars belonging to deans, chapters, and 
prebendaries, which are only exempted from 
the jurisdiction of the archdeacon ; these 
are derived from the bishop, who may visit 
them, and to whom there lies an appeal. 
PEDALS. See Organ. 
PEDALIUM, a genus of the class and 
order didynamia angiospermia. The cal. is 
rive-parted ; the cor. five-cleft ; nect. suba- 
ceous ; seeds two. There is one species, an 
annual of the East Indies. 
PEDESTAL. See Architecture. 
PEDICELLARIA, a genus of insects, of 
the order vermes mollusca : the generic cha- 
racter is, body soft and seated on a rigid pe- 
duncle ; aperture single. There are three 
species. The P. tridens inhabits the north 
seas, among the spines of echini: nect. 
smooth, hyaline, sometimes reddish ; lobes ot 
the head sometimes four, and three times as 
long as the neck, rarely unarmed with awn ; 
peduncle reddish, and three times as long as 
the neck. See Plate Nat. Hist. fig. 319. 
PEDICULARTS, red-rattle, or louse- 
wort, a genus of the didynamia angiospermia 
class of plants, the corolla whereof consists 
of a single ringent petal; the tube is oblong 
and gibbous ; the upper lip galeated, erect, 
compressed, and eniarginated ; the under 
one is patent, plane, semitrifid, and obtuse ; 
the fruit is a roundish acuminated capsule ; 
the seeds are numerous, roundish, compress- 
ed ant] covered. There are 19 species. 
Tips plant is of a cooling and dry ing 1 ature, 
whence it is recommended in fistulas and 
other sinous ulcers. It also stops hemorr- 
hages and tlie menses. 
PEDICULUS, louse, a genus of insects 
of the order aptera : the generic character is, 
legs six, formed for walking ; mouth furiu.- a- 
ed with an exsertile piercer; antennas the 
length of the thorax ; abdomen depressed, 
sublobated. 
This is a very numerous genus of insects,^ 
far more remarkable for variety than ele- 
gance of appearance. Of these strange and 
unpleasing animals some infest the bodies ot 
quadrupeds, others of birds, and some even 
those of insects themselves. It must, how- 
ever, be here observed, that many small in- 
sects, infesting other animals, have been 
often referred to the genus pediculus, which 
in reality belong to tnose of acarus, mono- 
culus, &c. &c. 
The pediculus humanus, or common louse, 
is so well known as to render any particular 
description unnecessary. As a species, it is 
distinguished by its pale livid colour, and lo- 
bated, oval abdomen. It is produced from, 
a small oval egg, properly called by the 
name of a nit, which is fastened or agglu- 
tinated by its smaller end to the hair on 
which it is deposited. From this egg pro- 
ceeds the insect, complete in all its parts, 
and differing only from the parent animal in 
iis smaller size. Such diminutive specimens 
are far preferable, for microscopic observa- 
tion, to the full-grown insects, shewing in a 
more distinct manner the disposition of the 
viscera, muscles, &c. &c. vV hen thus ex- 
amined by the microscope, the principal ap- 
pearances are as follow, viz. 1 he trunk or pro- 
boscis, which is generally concealed in its 
sheath or tube, is of a very sharp form, and is 
furnished towards its upper part with a tew 
reversed aculei or prickles ; the eyes are 
.arge, smooth, and black : the stomach and 
intestines, which possess the greater part of 
the abdominal cavity, afford an extremely 
distinct and curious view of the peristaltic 
motion; while the ramifications ot the 
tracheae, or respiratory tubes, appear dispers- 
ed in an elegant manner throughout various 
parts of the animal, and are particularly ob- 
servable towards their orifices on the sides 
of the abdomen; the legs are each termi- 
nated by a double claw, not greatly unlike 
that of a lobster, but of a much sharper form ; 
and the whole animal is every where covered 
by a strong granulated skin. It is affirmed by 
Lewenhoek, that the male is furnished at 
the extremity of the abdomen with a sting, 
and that it is this extremity which causes 
the chief irritation suffered from these ani- 
mals ; the suction of the proboscis hardly 
seeming to have caused any perceptible pain 
on the skin of his band. The male is readily 
distinguished from the female by having the 
tail or tip of the abdomen rounded; in the 
female it is forked or bifid. r l he same accurate 
observer (Lewenhoek), being desirous ot 
learning the proportion and time of the in- 
creasing of these insects, placed two female s 
in a black silk stocking, which he wore day 
and night tor that purpose. He found that 
in six days, one ot them liad lain Irit) 
and upon dissecting it, he found as 
more in the ovary ; he therefore cc. 'dueled 
ny 
