Recently, another method of treatment has been carried out by Cotterill.[16] A large semilunar flap is made from the occipital region, exposing the bone. Trephine circles are made on either side of the median ridge, and the intermediate part of the bone, together with the posterior part of the foramen magnum, is removed. The dura mater is opened and the occipital sinus ligatured. The lateral lobes of the cerebellum are then held apart, and the thickened arachnoid over the posterior part of these lobes and over the roof of the fourth ventricle exposed. This roof is opened. The wound is then closed. By this method drainage from the ventricle is said to be reestablished. Though without personal experience of this extensive procedure, one cannot avoid expressing considerable doubt as to its advisability. My own experience would lead me to the following conclusions:-- 1. Whilst recognizing that internal hydrocephalus usually demands surgical interference, it is only in some few cases that material benefit results. Some recent successful cases point to the possibility of better results in the future. 2. The operation which promises the best results, combined with the least risk to the patient’s life, is that described as ventriculo-subdural drainage. [4] _Der Hirnbruch und seine Behandlung._ Moscow, 1896. [5] _De la céphalhydrocèle traumatique_ (_Travaux de Neur. Chir._, iii. 1898). [6] _Archives Italiennes de Biologie_, vol. xxxviii, p. 444. [7] _Der Hirnbruch und seine Behandlung._ Moscow, 1896. [8] _Beitr. zur klin. Chir._, vol. iii, p. 228. [9] _St. Bart. Hosp. Reports._ Lawrence Ward. May 5, 1896. [10] _Beitr. zur klin. Chir._, vol. vii, p. 228. [11] _American Practice of Surgery._ Bryant and Buck. [12] _Tumours, Innocent and Malignant._ Bland Sutton. [13] _Brain_, 1902, p. 140. [14] In estimating the size of the head, the following tables--after Bonnifay--will be useful:-- _Age._ _Circumference of head_ (average). Birth to fifteenth day 343 millimetres (approximate). Fifteenth day to 2 months 368 „ „ At 3 months 388 „ „ Six months to 1 year 429 „ „ One year to 2 years 459 „ „ _Normal rapidity of growth of the head_ During the first 3 months 44 millimetres (approximate). During 3 to 6 months 41 „ „ From 6 months to 1 year 30 „ „ During second year 14 „ „