A spider IS considered dominant. I didn't say it wasn't. If it was written as SS, then 100% of the babies would be spider. The S represents the dominant spider gene. The spider will only pass on one allele, so if you hatch out ANY normals from a spider X something pairing, it has to be Ss because the spider obviously did not give the spider gene.

I will search for it. Sorry I'm pretty much the resident "doesnotusethesearchfunctionlikeanidiot" person.