  While the sequence of primes is very well distributed in the reduced residue
classes (mod $q$), the distribution of pairs of consecutive primes among the
permissible $\phi(q)^2$ pairs of reduced residue classes (mod $q$) is
surprisingly erratic. This paper proposes a conjectural explanation for this
phenomenon, based on the Hardy-Littlewood conjectures. The conjectures are then
compared to numerical data, and the observed fit is very good.
