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GES Sa. ie 
ABDOMEN (Lat. abdo, I conceal), The posterior cavity of the body, contain- 
ing the intestines and others of the viscera. In many Invertebrates there 
is no separation of the body-cavity 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. 
Acrovus (Gr. akros, high ; odous, tooth). A genus of the Cestraciont fishes. 
so called from the elevated teeth. 
AcrocEns (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. 
AcroTReETA (Gr. akros, high; trétos, pierced). A genus of Brachiopods, so 
called from the presence of a foramen at the summit of the shell. 
ACTINOCRINUS (Gr. aktin, aray; krinon, a lily). A genus of Crinoids. 
Actinozoa (Gr. aktin, a ray; and zoén, an animal). That division of the 
Celenterata of which the Sea-anemones may be taken as the type. 
ARGLINA (4g/é, a sea-nymph). A genus of Trilobites. 
JEPIORNIS (Gr. aipus, huge; ornis, bird). <A genus of gigantic Cursorial 
birds. 
AGNOSTUS (Gr. a, not; gignosko, I know). A genus of Trilobites. 
AULCES (Lat. alces, elk). The European Elk or Moose. 
ALECTO (the proper name of one of the Furies). A genus of Polyzoa. 
ALETHOPTERIS (Gir. aléthés, true; pteris, fern). A genus of Ferns. 
ALG (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. ambdén, a boss; onux, claw). A genus of Paleozoic Bi- 
valves. 
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. 
AMMONITIDZ. 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; zodn, animal). A name some- 
times 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. 
AmpuHicyon (Gr. amphi, both—implying doubt; kuén, dog). An extinct 
genus of Carnivora. 
