cribellum

/ (krɪˈbɛləm) /

a sievelike spinning organ in certain spiders that occurs between the spinnerets

Word Origin for cribellum

C19: New Latin, from Late Latin cribellum, diminutive of Latin cribrum a sieve

Cribellum, kri-bel′um, n. an accessory spinning-organ of certain spiders—also Cribrell′um:—pl.

Chambers's Twentieth Century Dictionary (part 1 of 4: A-D) |Various
The cribellum in both these species is large and can easily be seen in front of the other spinnerets.

The Common Spiders of the United States |James Henry Emerton
The cribellum is large for the size of the spiders and can generally be plainly seen just in front of the other spinnerets.

The Common Spiders of the United States |James Henry Emerton
In the male the cribellum is rudimentary, and there is no calamistrum.

The Common Spiders of the United States |James Henry Emerton

There are two quite distinct types of regular webs made by spiders possessing a cribellum and a calamistrum.

Cornell Nature-Study Leaflets |Various