Equiparance
The logical and hemilogical relations belong to the old class of relations of reason, while relations in re are alogical. But there are a few not unimportant relations of reason which are likewise alogical. In my paper of 1867, I committed the error of identifying those relations constituted by non-relative characters with relations of equiparance, that is, with necessarily mutual relations, and the dynamical relations with relations of disquiparance, or possibly non-mutual relations. Subsequently, falling out of one error into another, I identified the two classes respectively with relations of reason and relations in re.
The "paper of 1867" is 'On a New List of Categories'
…an equiparance; that is, the relation of B to A is essentially the same as that of A to B, so far as the duality of the pair is concerned. But no equiparance whatever, with the exception of the very few that are necessary, such as identity, coexistence, etc., is a logically simple relation.
Which is the more primitive (or fundamental, or simple) form of relation, that of an Equiparance (i.e. a reciprocal relation), or that of a Disquiparance? I say that it is the Disquiparance, or rather, it is the Opponency, or relation of which a specialization may be a Disquiparance.