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W. RAE SHERKIFES
the early workers were not so meticulous in the care with which they noted parts and used them to separate animals-spiders were, as a rule, lumped with insects as Aptera (wingless forms). Even to-day in the wide sense of the term, a student of spiders (though strictly an Arachnologist or even more strictly an Araneologist) is called an entomologist, though modern entomology concerns itself solely with the study of insects, a truly enormous field.
It may seem easy to differentiate the spider as distinct from the ordinary insect which, as an adult, has one pair of feelers (antennae), two pairs of wings and six legs, each of five joints.* The insect also has often a markedly indirect development where the small creature emerging from the egg passes through an active larval and also a resting pupal stage before reaching maturity. But many insects are wingless and not a few have but a slight metamorphosis.
If we find then a small Invertebrate animal minus wings and antennae but with pedipalps and eight legs then we have an Arachnid. The Arachnids, however, include as chief types the spider, harvestman, scorpion and mite. There can be no confusion with the scorpion whose characteristic sting at the tip of the long "tail" and the strange, sensory "pectines" are peculiar to itself alone. But harvestmen (Phalangids) are often popularly called spiders and the dreaded red spider of our greenhouses is really a
mite.
4
How shall we then distinguish between harvestman, true spider and mite? The spider's body, as we have seen, consists of cephalothorax and abdomen joined by a waist." The abdomen is not segmented and bears at the end the characteristic bunch of spinnerets not found in any other animal. The harvestman has no waist and the abdomen is segmented. The mite, at least in the case of the red spider" has its body in one piece only. Figure 2.
For purposes of identifying our finds we must note very carefully in the spider (1) the parts of the pedipalp of the male (2) the shape of the epigyne of the female remembering that these criteria are valid only in the case of an adult. The immature young spider has either its palpal organ, if male, or its epigyne, if female, undeveloped. All such youthful spiders should never be kept, much less killed! When captured in the glass tube always examine the captive with a pocket lens and set free if not mature. For spiders are among the most useful animals we have and should never on any account be ruthlessly destroyed at sight. Since the develop- ment of the spider is direct the little spiderling resembles its parents in all but size and maturity of the sexual organs.
EXPLANATION OF FIGURES.
Figure 1. Nephila maculata. Fabr.
1. ventral view 9; 2. face 9; 3. dorsal view ; 4.9 with dwarf (after Karsch). The legs of the little ♂ should cer- tainly bend round the abdomen of the 9;
* The joints of the insect leg are the coxa, trochanter, femur, tibia and tarsus.
The External Anatomy of the Spider
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1. CHEL. chelicera; ST. sternum; PEDI. pedicel; B.L. book-
lung; EP epigyne; SP. spinnerets; AN. anus; 1, 2, 3, 4 legs,
2. PAT. patella; TA. tarsus; PED. pedipalp.
3. CAR. carapace; TIB. tibia; MTA. metatarsus.
4. TR. trochanter; FE. femur.
Figure 2. Spider, harvestman and mite (after Warburton).
Figure 1.
1. Spider with body in two parts cephalothorax and abdomen
separate, the abdomen is not segmented.
2. Harvestman with body in one piece which however shows the
cephalothorax and the segmented abdomen united together.
3. Mite with body in one piece only.
PED. pedipalp; AB. abdomen; SP. spinnerets; 1, 2, 3, 4 legs.
Nos. 1, 2 and 3 are original.
The Hong Kong Naturalist.
December 1932.
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