More information from my friend Dean who studied entomology at Cal while I was studying etymology: "Position is the key. Since all arachnids are thought to have come form an organism that had six pairs of appendages, they are viewed to have developed their appendages from that same proto-arachnid. The chelicerae are fangs in spiders but in scorpions, solpugids, and psuedoscorpions they are the mouth parts that macerate the prey. The pedipalps in solpugids and spiders are leg-like sensory organs that test or taste the substrate. Adult, male spiders have the pedipalps modified into a syringe-like intromitant organ. In scorpions and psuedoscorpions the pedipalps are claws. The best way to figure out which is which in a given arachnid is to count the pairs of legs from the posterior. There are four pairs of real legs in almost all arachnids. Then the first pair of appendages anterior to the legs is the pedipalps followed by the chelicerae which are closest to the oral cavity."

[Corrected typo.]

Last edited by zmjezhd; 10/08/06 06:23 PM.
Ceci n'est pas un seing.