518 
P T I 
PUL 
P U L 
ceptacle is full of multipartite bristles; the 
pappus a little p'umy ; the calyx imbricated. 
r lhere are 18 species, shrubs oi' the Cape. 
PI EROSRERMUM, a genus of the po- 
lvandria order, in the monadelphia class of 
pi nts, and in the natural method ranking 
under the 37th order, columnifera. The 
calyx is quinquepartite ; the corolla consists 
of live oblong spreading petals. The fila- 
ments are about fifteen, which unite towards 
the base into a tube. The style is cylindri- 
cal; the capsule is oval, woody, and quin- 
quelocular, each of which are bivalved, con- 
taining many oblong, compressed, and winged 
seeds. 1 here are two species, natives of the 
Last Indies; the wood of which is very hard, 
and very like that of the holly-tree. 
P I EROTRAC1IEA, a genus of the ver- 
mes mollusca. Body detached, gelatinous, 
with a moveable fin at the abdomen or tail; 
eyes two, placed within the head. There are 
four species, that inhabit chiefly the Archipe- 
lago. 
PTINUS, a genus of insects belonging to 
the order coleoptera. The generic charac- 
ter is, antennae filiform, with the three last 
joints largest ; thorax roundish, without di- 
stinct margin, receiving occasionally the 
head. 
The genus ptinus, like that of dermestes, 
consists of small insects, which, in general, 
have similar habits, living both in their larva 
and complete state among dry animal sub- 
stances ; and some species in dry wood, com- 
mitting great havoc among the older articles 
of furniture, which they, pierce with innu- 
merable holes, thus causing their gradual 
destruction. 
'To this genus belongs the celebrated in- 
sect, distinguished by the title of the death- 
watch, or ptinus fatidicus. Among the po- 
pular superstitions which the almost general 
iliuminatioil of modern times has not been 
able to obliterate, the dread of the death- 
watch may well be considered as one of the 
most predominant, and still continues to dis- 
turb the habitations of rural tranquillity with 
groundless fears and absurd apprehensions. 
It is not indeed to be imagined that those 
who are engaged in the more important cares 
of providing the immediate necessaries of 
life, should have either leisure or inclination 
to investigate with philosophic exactness the 
causes of a particular sound; yet ;t must be 
allowed to be a very singular circumstance 
that an animal so common should not be 
more universally known, and the peculiar 
noise which it occasionally makes be more 
universally understood. It is chiefly in the 
advanced state of spring that this alarming 
little animal commences its sound, which is 
no other than the call or signal by which the 
male and female are led to each other, and 
which may be considered as analogous to the 
call of birds, though not owing to the voice 
of the insect, but to its beating on any hard 
substance with the shield or fore-part of its 
head. The prevailing number of distinct 
strokes which it beats is from seven to nine 
or eleven ; Which very circumstance may 
perhaps still add in some degree to the omi- 
nous character which it bears among the vul- 
gar. These sounds or beats are given in 
pretty quick succession, and are repeated at 
uncertain intervals ; and in old houses where 
the insects are numerous, may be heard at 
almost every hour of the day, especially if 
the weather is warm. The sound exactly 
resembles that which may be made by beat- 
ing moderately hard with a nail on a table. 
J lie insect is of a colour so nearly resembling 
that of decayed wood, viz. an obscure grey- 
ish brown, that it may for a considerable^tifne 
elude the search of the enquirer. It is 
about a quarter of an inch in length, and is 
moderately thick in proportion, and the wing- 
shells are marked with numerous irregular 
variegations of a lighter or greyer cast than 
the ground-colour. 
We must be careful not to confound this 
animal, which is the real death-watch of the 
vulgar, emphatically so called, with a much 
smaller insect of a very different genus, which 
makes a sound like the ticking of a watch, 
and continues it for a long time without in- 
termission. It belongs to a totally different 
order, and is the termes pulsatori urn of Lin- 
naeus. 
W e cannot conclude this slight account of 
the death-watch without quoting a sentence 
from that celebrated work the Pseudodoxia 
Epidemica of the learned sir Thomas Brown, 
who on this subject expresses himself in words 
like these: “ He that could eradicate this 
error from the minds of the people, would 
save from many a cold sweat the meticulous 
heads of nurses and grandmothers.” 
A very destructive little species of ptinus 
is often seen in collections of dried plants, 
&c. remarkable for the ravages it commits 
both in its larva and perfect state. The larva 
resembles that of a beetle in miniature, being 
about the eighth of an inch long, and of a 
thickish form, lying with the body bent, and 
is of a white colour, The perfect insect is 
very small, measuring only about the tenth 
of an inch, and is slender, of a pale yellowish 
chesnut-colour, appearing, when magnified, 
beset with small short hairs, with the wing- 
covers finely striped by rows of small im- 
pressed points or dots. The ravages of the 
larva are most remarkable during the summer. 
d he ptinus fur of Linnaeus is another very 
destructive species. Its length is somewhat 
more than the tenth of an inch, and its co- 
lour pale chesnut-brown, sometimes marked 
on the wing-covers by a pair of greyish bands ; 
the antenna* are rather long and slender; the 
body remarkably convex ; and the thorax, 
when magnified, appears to have a projecting 
point on each side. Its larva resembles that 
of the preceding species, and is found in si- 
milar situations. 
Pd OLEMAIC, or Ptolemean system of 
astronomy, is that invented by Claudius Pto- 
Iemsus, a celebrated astronomer and mathe- 
matician of PelusiuTh in Egypt, who lived in 
the beginning of the second century of the 
Christian aira. 
Phis hypothesis supposes the earth im- 
moveably fixed in the centre, not of the world 
only, but also of the universe; and that the 
sun, the moon, the planets, and stars, all move 
about it from east to west, once in- 24 hours, 
in the order following, viz. the moon next 
to the Earth, then Mercury, Venus, the Sun, 
Mars, .Jupiter, Saturn, the fixed stars, the 
first and second crystalline heavens, and above 
all, the fiction of their primum mobile. 
PUBES. See Anatomy. 
PI C ERON. See Aphis. 
PULEX, the flea, a genus of insects of the i 
order aptera. Lie generic character is, legs I 
six, formed for leaping ; eyes two ; antennae i 
filiform ; mouth furnished with an inflected, 
setaceous snout, concealing a piercer ; abdo- 
men compressed. 
'Phis genus is one of the most singular in 
the order aptera. The pulex irritans, or 
common flea, so well known in its complete 
state in every region of the globe, is remark- 
able for undergoing the several changes ex- 
perienced by file major part of the insect 
race ot other tribes ; being produced from an 
egg, in the form of a minute worm or larva, 
which changes to a chrysalis, in order to give 
birth to the perfect animal. The female flea 
deposits, or rather drops, her eggs at distant 
intervals, in any favourable situation : thev 
are very small, of an oval shape, of a white 
colour, and a polished surface From these, 
in the space of six days, are hatched the lar- 
va*, which are destitute of feet, of a length- 
ened worm-like shape, beset with distant 
hairs, and furnished at the head with a pair of 
short antennae or tentacula, and at the tail 
with a pair of slightly curved forks or holders. 
Their colour is white, with a reddish cast, 
and their motions quick and tortuous. These 
larvae are very frequently found in the nests 
of various birds, and, in particular, of pigeons, 
where they fasten occasionally to the’Pyouna* 
brood, and saturate themselves with olood° 
In the space of ten or twelve days, they ar- 
rive at their full growth, when they usually 
measure near a quarter of an inch in length. 
At this period they cease to feed, and, casting 
their skin, change into the state of a chry- 
salis, which is of a white colour, and of an 
oval shape, with a slightly pointed extremity, 
and exhibits the immature limbs of the in- 
cluded insect. The larvae are said to spin 
themselves up in an oval cotton-like cover- 
ing before they undergo their change. This, 
however, is not always the case. After ly- 
ing for the space of twelve days in chry- 
salis, the complete insect emerges in its per- 
fect form. It now begins to exert its lively 
motions ; and employs the sharp proboscis 
with which nature has furnished it, in order 
to obtain nourishment from the first man, 
bird, or quadruped, to which it can gain ac- 
cess. 'I he time required for the evolution of 
this animal varies considerably according to 
the season of the year, and in the winter 
months is of much longer duration than the 
period above-mentioned ; the egg scarcely 
hatching under twelve days, and the larvae 
lying nearly twice the usual time in chrysalis. 
Among the chief singularities observable 
in the structure of the flea, may be noticed 
the extraordinary situation of the first pair of 
legs, which, instead of being placed beneath 
the thorax, as in most other insects, are situ- 
ated immediately beneath the head ; the an- 
tenna? are short, hairy, and consist of five 
joints ; and at a small distance beneath there 
is placed the proboscis, which is strong, sharp- 
pointed, tubular, and placed between a pair 
of jointed guards. or sheaths, which are still 
farther strengthened at the base by a pair of 
pointed scales; the eyes are large, round, 
and black. The general appearance of the 
animal is too well known to require particu- 
lar description : it may only be necessary to 
observe, that the male is considerably smaller 
than the female, with the back rather sinking 
than convex, as it always is in the female in- 
sect. Nothing can exceed the curious dis- 
position and polished elegance of the shelly 
armour with which the animal is covered. 
