a
singular Sarcoptes-like mite, as they were found on the same specimen of
Woodpecker at about the same date, and it is known that the growth of
mites is rapid, the metamorphoses, judging by the information which we
now possess, occupying usually but a few days.

[Illustration: 143. Egg-eating Mite.]

The young (though there is, probably, a still earlier hexapodous stage)
of this Sarcoptid has an elongated, oblong, flattened body, with four
short legs, provided with a few bristle-like hairs, and ending in a
stalked sucker, by aid of which the mite is enabled to walk over smooth,
hard surfaces. The body is square at the end, with a slight median
indentation, and four long bristles of equal length. They remained
motionless in the groove on the barb of the feather, and when removed
seemed very inert and sluggish. A succeeding stage of this mite, which
may be called the pupal, is considerably smaller than the larva and
looks somewhat like the adult, the body having become shorter and
broader. The adult is a most singular form, its body being rudely ovate,
with the head sunken between the fore legs, which are considerably
smaller than the second pair, while the third pair are twice as large as
the second pair, and directed backwards, and the fourth pair are very
small, not reaching the extremity of the body, which is deeply cleft and
supports four long bristles on each side of the cleft, while other
bristles are attached to the legs and body, giving the creature,
originally ill-shapen, a haggard, unkempt appearance. The two stigmata
or breathing pores open near the cleft in the end of the body, and the
external opening of the oviduct is situated between the largest and
third pair of legs. No males were observed. In a species of Acarus
(Tyroglyphus), somewhat like the Cheese mite, which we have alive at
the time of writing, in a box containing the remains of a Lucanus larva,
which they seem to have consumed, as both young and old are swarming
there by myriads, the young are oval and like the adults, except that
they are six-legged, the fourth pair growing out after a succeeding
moult.

Such is a brief summary of what has been generally known regarding the
metamorphoses of a few species of mites. In a few kinds no males have
been found; the females have been isolated after being hatched, and yet
have been known to lay eggs, which produced young without the
interposition of the males. This parthenogenesis has been noticed i