When it is contrary to the natural order of the venereal act . . . this is called "an unnatural vice," which may happen in several ways.1. by procuring pollution, without any copulation, for the sake of venereal pleasure: this pertains to the sin of "uncleanness" which some call "effeminacy."2. by copulation with a thing of undue species, and this is called "bestiality."3. by copulation with an undue sex, male with male, or female with female, as the Apostle states (Rm. 1:27): and this is called