Entomology : with special reference to its biological and economic aspects . s sepa-rate, anterior in position (on the second segment of the body).Example, Spiroholus (Fig. 4). Chilopoda.—Terrestrial. Two regions, head and long and flattened, with numerous segments, each of which bears a pair of long six-or seven-jointed limbs, which arenot inserted near the median simple and numerous (ag-glomerate in Scutigcra), antennaelong. A pair of mandibles andtwo pairs of maxillae. A singlegenital opening, on the preanalsegment. Example. Scolopciidra (I^^ig- 5)- Insecta (Hexapoda), —
Entomology : with special reference to its biological and economic aspects . s sepa-rate, anterior in position (on the second segment of the body).Example, Spiroholus (Fig. 4). Chilopoda.—Terrestrial. Two regions, head and long and flattened, with numerous segments, each of which bears a pair of long six-or seven-jointed limbs, which arenot inserted near the median simple and numerous (ag-glomerate in Scutigcra), antennaelong. A pair of mandibles andtwo pairs of maxillae. A singlegenital opening, on the preanalsegment. Example. Scolopciidra (I^^ig- 5)- Insecta (Hexapoda), — Pri-marily terrestrial. Three distinctregions—head, thorax and abdo-men. Head with a pair of com-pound eyes in most adults, onepair of antenna; and three pairsof mouth parts—mandibles, max-ilke and labium—besides whicha hypopharj^nx, or tongue, is])resent. Thorax with a pair oflegs on each of its three segmentsand usually a pair of wings oneach of the posterior two seg-ments : though there mav be onlyone pair of wings (as in Dipteraand male Coccidae) ; the pro-. A centipede, Scolopendra two thirds the maximum length. thorax never bears wings. Ab- domen typically with ten seg-ments (seldom more) and without legs, elccqiting in somelarvae (as those of Lepidoptera. Tenthredinidre and Panor- CLASSIFICATION 5 pidie). Stigmata paired and segmentally arranged. A meta-morphosis (direct or indirect) occurs except in Thysanura andCollembola. Relationships.—The interrelationships of the classes ofArthropoda form an obscure and highly debatable subject. Crustacea and Insecta agree in so many morphologicaldetails that their resemblances can no longer be dismissed asresults of a vague parallelism. or convergence of devel-opment, but are inexplicable except in terms of community oforigin, as Carpenter has lately insisted. Arachnida are extremely unlike other arthropods but findtheir nearest allies among Crustacea, particularly the fossilforms known as trilobites. Mala
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
