In Parisé’s case the child was fourteen days old. The lower lip was cleft through its whole thickness in the median line. The free edges were rounded as in harelip, and the cleft was continued below as a cicatricial band in the middle line of the neck as far as the sternal notch. The mandible was in two portions, which were separated from one another by a distance of two or three millimetres, bridged across by connective tissue. The tongue was entirely divided, the cleft extending back to the glosso-epiglottic ligament, and downwards between the genio-hyo-glossi muscles; each half was covered throughout with mucous membrane, and was bound to the corresponding side of the jaw by a mucous ligament or frænulum. * * * * * As to the _ætiology_ of these defects, but little is known. _Heredity_ is an undoubted factor in their production, and an investigation of the family history will in many cases elicit a confirmation of such an idea. Thus in two instances in my own practice I have been able to determine that the father, grandmother, and great-grandfather had all suffered from harelip to a greater or less extent. Mason in his book mentions several other illustrations of this fact. Liston operated on four members of one family for harelip. M. Demarquay[31] related a case in the Surgical Society of Paris, in which, from the grandparents downwards, eleven children had been born with harelip. In the ‘British Medical Journal’[32] a correspondent related his own family history, stating that it had occurred in some branch or other for the past hundred years. An examination of the parents’ mouths should always be made when possible, and very commonly it will be found that one or both possess a short upper lip, and a high arched narrow palate. In others there is a slight groove in the alveolar process between the central and lateral incisors. I have also observed a small symmetrical crease on either side of the median line in the upper lip, indicating a tendency to, if not a natural intra-uterine cure of, a double harelip. In some instances the deformity dies out of families, possibly from the fact that the defective condition in one parent is remedied by a more perfect development in the other; whilst in others the tendency distinctly increases, and a father or a mother with harelip will beget a family where three out of the four or five children will be similarly affected. By a proper selection of mates this deformity could probably be bred out, as well as bred up to.