Throughout, by relation we mean a binary relation. Let Rel(X) be the set of all binary relations on the set X. An algebra of relations is a pair (Φ, Ω) where Ω is a set of operations on relations and Φ ⊂ Rel(X) is a set of relations closed under the operations of Ω. Each algebra of relations can be considered as ordered by the set-theoretic inclusion ⊂. Denote by M {Ω} the class of all algebras isomorphic to ones whose elements are relations and whose operations are members of Ω. The class M {Ω, ⊂} is determined in the same way.We will consider the following operations on relations: relation product •, relation inverse −1 , intersection ∩, diagonal relation ∆, and the unary operation *