Where a word has more than one ending, the difference is given after a hyphen which represents the stem word: e.g. ametabola -ous; the latter in place of ametabolous, which indicates the possession of the characters peculiar to the ametabola. Where there is an English and a Latin ending, the former is usually given with the word and the other is added: e.g. aequilate -us, instead of aequilatus, there being no difference in the application. Usually the singular form of the word is first given, and the plural ending is added; e.g. antenna -ae, cenchrus -ri, desideratum -ata; but occasionally, when the plural is more commonly used, e.g. epimera -eron, this is reversed and the singular ending is added: when the two are different in form, e.g. foot and feet, the words are given separately, and so when there is a difference in the application, as in uncus and unci. In the definition of color terms the words in brackets [ ] refer to the equivalent color as named on the plate, or the combination needed to produce it. The names in parentheses ( ) are those of the writers whose definitions are used, or who have used the term in the sense defined. In the terms of venation, these parentheses occur most frequently. Most of the signs and abbreviations are those in common use := equal to, or the same as; q.v. which see; pl. plural; abb. abbreviated. The abbreviated names are: Comst. for Comstock; Coq. for Coquillett; Meig. for Meigen; Nort. for Norton: O. S. for Osten-Sacken: and Will. for Williston. A A: prefix, is privative; wanting or without. Ab: off; away from. Abbreviated: cut short; not of usual length. Abdomen: the third or posterior division of the insect body: consists normally of nine or ten apparent segments, but actual number is a mooted question: bears no functional legs in the adult stage. Abdominal: belonging or pertaining to the abdomen. Abdominal feet: see pro-legs. Abdominal groove: the concave lobe of the inner margin of secondaries enveloping the abdomen beneath, in some butterflies. Abdominal pouch: in female Parnassiids, a sac-like ventral cavity, formed by material secreted during copulation. Abductor: applied to muscles that open out or extend an appendage or draw it away from the body: see adductor. Abductor mandibulae: the muscle that opens the mandibles. Aberrant: unusual; out of the ordinary course. Aberration: a form that departs in some striking way from the normal type; either single or occurring rarely, at irregular intervals. Abiogenesis: spontaneous generation. Abnormal: outside the usual range or course; not normal. Aborted: a structure developed so as to be unfit for its normal function obsolete or atrophied. Abraded: scraped or rubbed. Abrupt: suddenly or without gradation. Abscissus: cut off squarely, with a straight margin. Absconditus: hidden, concealed; retracted into another.