In his PhD thesis, Arnon [1] builds a completion of the Dickson algebras wh
ich contains a "free root" algebra D-f (in) on the top Dickson classes. Hu'
ng [5] has shown that this algebra is in fact isomorphic to a similar compl
etion (A(mu))* of the dual of the Steenrod algebra A*. Amen also completed
the Steenrod algebra A with respect to its halving homomorphism to obtain A
(mu). Here we study an analogous completion of the Dyer-Lashof algebra R to
obtain R-mu with canonical subcoalgebras R-mu[n]. Unlike the Steenrod alge
bra, we may further complete R-mu with respect to length to obtain (R) over
cap(mu). It turns out, somewhat surprisingly, that the dual ((R) over cap(
mu))* contains (A(mu))* as a dense subalgebra.