Dorsal decubitus is rightly regarded as the most correct position, physiologically speaking, for the woman to assume during coitus. That from the earliest times and in the most diverse races, this position has been customary, is shown by numerous antique paintings and statues, and by the reports of those who have studied the customs of savage races. Various other positions are, however, occasionally assumed; thus, _Ploss_ and _Bartels_ report, that among the Soudanese, coitus is practiced in the erect posture, with the man standing behind the woman; that among the Inuits (Eskimo), the act is performed in the manner usual among quadrupeds; that among the Swahelis in Zanzibar, and among the indigens of Kamschatka, the lateral posture is customary; and that among the Australian blacks, coitus is usually effected in the crouching posture, both parties squatting on their hams. The same writers remind us, that in the old calendars of the fifteenth, sixteenth, seventeenth, and eighteenth centuries, definite commands and prohibitions for the conduct of marital intercourse are to be found, and that lucky and unlucky days, respectively, are specified for the performance of the act. These recommendations would appear to be relics of antiquity, for in the Sanscrit work _Kokkogam_, under the heading “_Sexual Intercourse According to the Days of the Month_,” exact instructions are given for the proper performance of coitus. In the _Kamasutra_ (the Indian _ars amatoria_, a work only in recent days rendered accessible to European readers in the translation of _R. Schmidt_), several chapters are devoted to the detailed description of the various methods of copulation, and rules are given for the carnal union of man and wife. But, as the Indian author justly remarks, “Rules are of value only for the control of moderate desire; when the wheel of passion has once begun to roll, to prescribe a course is no longer of any avail.” In this work, sixty-four varieties of erotic enjoyment are enumerated, and we find an _explicatio coitus secundum mensuram, tempus, naturam, de modis inter coitum procumbendi, de minis coitibus, de coitu inverso, de viri inter coitum consuetudinibus_.