spiders are not arthropods
however mygalomorphs cannot produce the pirifom silk that the araneomorphae use as an instant adhesive to glue silk to surfaces or to other strands of silk and this makes web construction more difficult for mygalomorphs
 some triassic mygalomorphs appear to be members of the family hexathelidae whose modern members include the notorious sydney funnelweb spider and their spinnerets appear adapted for building funnelshaped webs to catch jumping insects