  The tetrus is a sort of big brother to the tripus, W.P. Thurston's example of
a compact hyperbolic 3-manifold with totally geodesic boundary. We describe a
sixfold cover of the double of the tetrus, itself a double, which fibers over
the circle with fiber a closed surface of genus 19. We also record
arithmeticity of the doubles and certain twisted doubles of the tripus and
tetrus, and point out some consequences regarding families of covers.
