Many of the languages under discussion have systems, which are usually obligatory, for indicating the owner of parts of the body, which are different from the systems used to indicate possession of other objects, as, for instance, a house. That is to say that one never, or virtually never, speaks about eyes, but always about his eyes, my eyes, etc. The criterion seems to be the alienability of the object, for there also exist special systems, usually of a third type, with regard to certain kinship terms. A number of Melanesian languages have far more extensive systems for classifying nouns on the basis of indications of possession. In the Geelvink Bay languages these systems are much less extensive and often even defective, which conveys the impression that they either never fully developed, or are in a state of decline and are mere survivals.