A strictly similar inquiry might be made into the system of the Crow. Here the almost complete coincidence of certain very unusual features with Hidatsa ones bears eloquent testimony to the exceptionally close genetic relationship of the two tribes. Thus, a wife who has been married before is distinguished by a specific word, and spouses generally refer to each other not by a specific term, which seems restricted to non-vocative usage, but by a demonstrative expression. Not only is there a confusion of generations according to the Hidatsa variant, but the mother’s brother is classed with the elder brother and so is the mother’s mother’s brother. The last-mentioned features are partly found among the Mandan. All three tribes differ from the other Siouans, and indeed from all other Plains Indians in having matrilineal descent. Since this is likewise the rule among genetically unconnected peoples sharing the Hidatsa variant, we regard the latter as functionally connected with the clan organization. But there are other traits in which the terminology of the Crow differs from that of their nearest congeners, and here we must systematically consider the possible effect of all such peoples as the Oglala, or Blackfoot, with whom they have come into contact. Such divergence may be merely the effect of internal readjustment. Thus, the Crow classification of the father’s sister’s husband with the father admits of a plausible interpretation as the result of another peculiarity--the classing of the father’s sister with the mother in direct address. Instead of having two deviations from the Hidatsa norm, we should thus have at bottom only one.