into thorax and abdomen, and it is only in the higher _Annulosa_
that a distinct abdomen can be said to exist.

ABERRANT (Lat. _aberro_, I wander away). Departing from the regular
type.

ABNORMAL (Lat. _ab_, from; _norma_, a rule). Irregular; deviating
from the ordinary standard.

ACRODUS (Gr. _akros_, high; _odous_, tooth). A genus of the
Cestraciont fishes, so called from the elevated teeth.

ACROGENS (Gr. _akros_, high; _gennao_, I produce). Plants which
increase in height by additions made to the summit of the stem
by the union of the bases of the leaves.

ACROTRETA (Gr. _akros_, high; _tretos_, pierced). A genus of
Brachiopods, so called from the presence of a foramen at the summit
of the shell.

ACTINOCRINUS (Gr. _aktin_, a ray; _krinon_, a lily). A genus of
Crinoids.

ACTINOZOA (Gr. _aktin_, a ray; and _zooen_, an animal). That division
of the _Coelenterata_ of which the Sea-anemones may be taken as
the type.

AEGLINA (_AEgle_, a sea-nymph). A genus of Trilobites.

AEPIORNIS (Gr. _aipus_, huge; _ornis_, bird). A genus of gigantic
Cursorial birds.

AGNOSTUS (Gr. _a_, not; _gignosko_, I know). A genus of Trilobites.

ALCES (Lat. _alces_, elk). The European Elk or Moose.

ALECTO (the proper name of one of the Furies). A genus of _Polyzoa_.

ALETHOPTERIS (Gr. _alethes_, true; _pteris_, fern). A genus of
Ferns.

ALGAE. (Lat. _alga_, a marine plant). The order of plants comprising
the Sea-weeds and many fresh-water plants.

ALVEOLUS (Lat. _alvus_, belly). Applied to the sockets of the
teeth.

AMBLYPTERUS (Gr. _amblus_, blunt; _pteron_, fin). An order of
Ganoid Fishes.

AMBONYCHIA (Gr. _ambon_, a boss; _onux_, claw). A genus of Palaeozoic
Bivalves.

AMBULACRA (Lat. _ambulacrum_, a place for walking). The perforated
spaces or "avenues" through which are protruded the tube-feet,
by means of which locomotion is effected in the _Echinodermata_.

AMMONITIDAE. A family of Tetrabranchiate Cephalopods, so called
from the resemblance of the shell of the type-genus, _Ammonites_,
to the horns of the Egyptian God, Jupiter-Ammon.

AMORPHOZOA (Gr. _a_, without; _morphe_, shape; _zooen_, animal).
A name sometimes used to designate the _Sponges_.

AMPHIBIA (Gr. _amphi_, both; _bios_, life). The Frogs, Newts,
and the like, which have gills when young, but can always breathe
air directly when adult.

AMPHICYON (Gr. _amphi_, both--implying doubt; _kuon_, dog). An
extinct genus of _Carnivora_.

AMPHILEST