_Menstruation began._ _Duration of the sexual life._ In 5 cases in the 8th to the 10th year Averaging 36.60 years. In 70 cases in the 11th to the 13th year Averaging 33.65 years. In 110 cases in the 14th to the 16th year Averaging 30.85 years. In 56 cases in the 17th to the 19th year Averaging 28.35 years. In 9 cases in the 20th year or later Averaging 20.45 years. A further analysis of these 250 cases is given by Guy in the following table: _First appearance of menstruation._ _Average age at _Duration of which menstrual menstruation activity._ ceased, in years._ In 1 case in the 8th year 42 34 years. In 2 cases in the 9th year 46 37 years. In 2 cases in the 10th year 47 37 years. In 10 cases in the 11th year 47.10 36.10 years. In 29 cases in the 12th year 45.34 33.34 years. In 31 cases in the 13th year 46.16 33.16 years. In 39 cases in the 14th year 45.33 31.33 years. In 40 cases in the 15th year 46.30 31.30 years. In 41 cases in the 16th year 46.14 30.14 years. In 26 cases in the 17th year 45.18 28.18 years. In 19 cases in the 18th year 46.87 28.87 years. In 11 cases in the 19th year 46.18 27.18 years. In 5 cases in the 20th year 40.80 20.80 years. In 3 cases in the 21st year 41.66 20.66 years. In 1 case in the 23d year 41 18 years. _Hannover_ also gives data respecting the relation between the duration of menstrual activity and the early or late appearance of menstruation. These data are tabulated as follows: