where C represents the canine, I₁ and I₂ the central and lateral incisors, and the double lines indicate the position of the clefts. Careful examination of a considerable number of skulls has brought much confirmatory evidence to light, indicating the truth of the above proposition. Thus, to pick out a few facts from the mass of material available:—Sabourand[53] records two cases of unilateral harelip with cleft palate, one of which died at the age of thirty-three days. In each the dentition was typically that described by Albrecht, viz. four teeth on the side of the cleft (two molar, one canine, and one precanine), and six on the opposite (two median incisors, one lateral incisor, one canine, and two molars). Broca[54] has reported a case of a much deformed fœtus stillborn at seven months. In this there was cleft palate and double harelip with the os incisivum freely moveable, but not displaced. The bone was found to consist of two little masses, mobile on each other, and each containing two incisor germs; and on each side external to the cleft there was a precanine similar in shape to the incisors. The middle one of these three incisors was distinctly the least developed. Again, Sir William Turner[55] has carefully investigated the dentition, as seen in casts obtained from various hospitals, of fifteen specimens of alveolar harelip, eight of which were single left-sided, four single right-sided, and three double clefts. To these he adds the records of forty-nine preparations examined and reported on by Kölliker;[56] we can here, therefore, discuss the dentition of sixty-four cases. They may be divided into two groups: (α) In which no precanine intervened between the cleft and the canine—thirteen cases. (β) In which a precanine existed between the cleft and the canine—fifty-one cases. In not a few instances the os incisivum contained four teeth, and yet a precanine existed external to the cleft, _i. e._ in hexaprodontous jaws the cleft passed between the middle and outer precanines.