Entomology : with special reference to its biological and economic aspects . Cat and dog flea, Ctenocephalns canis. A, larva (after Kunckel dHerculais) ;B, adult. Length of adult, 2 mm. Suborder Aculeata (Heterophaga, Petiolata).—Abdomenpetiolate or subpetiolate; first abdominal segment transferredto the thorax. Ovipositoroften modified to form asting. Larvae apodous. Ex-ample, Apis (Fig. 277). Interrelations of theOrders.—The modern clas-sification aims to expressrelationships, and these aremost clearly to be ascer-tained by a comparativestudy of the facts of anat-omy and development. The mos
Entomology : with special reference to its biological and economic aspects . Cat and dog flea, Ctenocephalns canis. A, larva (after Kunckel dHerculais) ;B, adult. Length of adult, 2 mm. Suborder Aculeata (Heterophaga, Petiolata).—Abdomenpetiolate or subpetiolate; first abdominal segment transferredto the thorax. Ovipositoroften modified to form asting. Larvae apodous. Ex-ample, Apis (Fig. 277). Interrelations of theOrders.—The modern clas-sification aims to expressrelationships, and these aremost clearly to be ascer-tained by a comparativestudy of the facts of anat-omy and development. The most generalized, orprimitive, insects are theT h y s a n u r a. Subtracting their special, or adaptive, peculiarities, their remaining charac-ters may properly be regarded as inheritances from somevanished ancestral type of arthropod. This primordial type,. columba. A, imago; B, larva(with parasitic larva of Thalessa attached).Natural size.—After Riley. 2 2 ENTOMOLOGY then, probably bad three simple and equal thoracic segmentsdiffering- but slightly from the ten abdominal segments; threepairs of legs and no wings; three pairs of exposed bitingmouth parts; a pair of long many-jointed antennge and a pairof cerci of the same description; a thin naked integument; asimple straight alimentary canal distinctly divided into threeprimary regions; a ganglion and a pair of spiracles for eachof the three thoracic and the first eight abdominal segments,if not all the latter; no metamorphosis; functional abdominallegs and active terrestrial habits. The existing form that best meets these requirements isScolopendrella, which is not an insect, however, but belongsamong or near the diplopods. The most primitive of knowninsects are Aiiajapyx and Canipodca, through which otherinsects trace their origin to the stock from which Symphylaand Diplopod
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
