This spider is in the genus Cicurina, also known as the Cave Meshweaver or Cave Spider. Pronounced “sik-uhr-EYE-nuh,” the Latin name translates to “tame” or “mild.”
From Buggide.net and according to Rod Crawford:
Cicurina of Western Washington: “C. pusilla is by far the commonest. C. simplex and C. “idahoana” (really an undescribed species related to idahoana, in my opinion) are moderately common. Cicurina tersa is less common than the previous three. The other Cicurina of western Washington are actually rare here, C. tacomaand C. intermedia.” ~Rod Crawford
Adams, R.J. 1970. Field Guide to the Spiders of California and the Pacific Coast States. California Natural History Guides. University of California Press. Los Angeles.