Of the specific forms of marriage the levirate has already been considered and the cross-cousin marriage briefly mentioned. Dr. Rivers has demonstrated the close dependence of nomenclature on the latter practice in Melanesia. Here the custom itself is found in full swing, and it would be unreasonable to deny that the terminology had its origin in this usage even in parts of Melanesia where it cannot be observed. This does not mean that cross-cousin marriage necessarily obtained throughout the range of distribution of the corresponding terminology but that the terminology spread from a center where it reflected the social institution. Thus, in Guadalcanar the cross-cousin marriage still persists and we find cross-cousins, brothers-in-law and sisters-in-law comprised under a single appellation. In Anaiteum, cross-cousins of opposite sex address one another by the terms used for husband and wife.[63] It seems to me methodologically quite justifiable to interpret similar features in neighboring islands as having their ultimate origin in cross-cousin marriage. But the argument fails where similar connotations of terms occur without evidence of the marriage rule unless it can be demonstrated that no other cause could have produced the result. Thus, I must consider unsuccessful Dr. Rivers’ attempt to deduce, though with qualifications, the former existence of the institution in question from the system of the Dakota Indians.[64] The classification of brothers-in-law with cross-cousins might be simply a reflection of the dual organization, by which these relatives would fall within the same group; or, to put it differently, if the term cross-cousin is given the wide significance with which we are familiar in primitive systems, so as to include members of the opposite moiety and one’s own generation, a man’s brothers-in-law are necessarily members of the cross-cousin class. The superiority of the moiety hypothesis in this instance lies in the fact that the dual organization occurs among several contiguous and related tribes while the cross-cousin marriage is extremely rare in North America and its highest development occurs among remote peoples of the Pacific region. Regarding special forms of marriage, it is rather important to ascertain whether the terms used by our authorities are to be interpreted in our own or in the more inclusive primitive sense. For example, Tylor reduced the institution of cross-cousin marriage to the principle of exogamous moieties by assuming the wider significance.[65] As Dr. Rivers points out,[66] the two rules are not identical if marriage is prescribed with the own daughter of the own mother’s brother. In that case, the moiety rule is only a larger framework with which the specific institution is not incompatible but which does not determine cross-cousin marriage. Looking at the matter chronologically, I can even conceive the development of larger social groups from such specific marriage regulations.