(ii) That in other defects accessory structures are sometimes produced in the neighbourhood, as if Nature, being baulked in her efforts of development at one spot, expends her energies in some less useful addition elsewhere. The accessory auricles and auricular appendages seen in macrostoma are cited as illustrations of this; and any precanine external to the cleft is maintained to be of a similar character. Whilst fully admitting the plausibility of such teaching, I cannot see that it explains such osseous development as occurs in Albrecht’s Kiel skulls, or such a regular appearance of an incisor external to the cleft as that indicated by the figures quoted above. The less frequent existence of an accessory tooth in the os incisivum seems much more readily explicable on such a ground. * * * * * To summarize the principal points as to the development of ordinary harelip: 1. That the intermaxilla is derived from the union of four ossific portions, two on either side of the median line, and that these are to be known respectively as the endo- and meso-gnathion, whilst the superior maxilla is termed the exognathion. 2. That these ossific portions are developed from the internal and external nasal projections of the fronto-nasal process respectively, and that ordinarily the central and lateral incisors are developed one from each segment. Occasionally an accessory incisor is developed between the other two from the endognathion. 3. That the external nasal process does not enter into the formation of the upper lip, but terminates superficially in the depression immediately below the ala nasi (see p. 57). 4. That simple harelip, where the cleft is limited to the soft parts, is due to the non-union of the superficial portions entering into the formation of the lip. 5. That in alveolar harelip the cleft passes between the endo- and meso-gnathion. 6. That the os incisivum consists merely of the two united endognathia, and normally carries only the two central incisors. Any additional tooth is not the normal lateral incisor, but an accessory one, probably due to the reappearance of an old suppressed member. 7. That any precanine existing on the outer side of the cleft is the normal lateral incisor, springing from the mesognathion; but that the latter portion of bone is rarely seen as a separate entity in human skulls possessing such deformity, from early obliteration of the suture between it and the maxilla, and that it is often badly developed and the lateral incisor stunted or undeveloped from defective vascular supply. * * * * * Having entered thus fully upon the question as to the situation of the cleft in alveolar harelip, we must now turn to the consideration of the morphological position of the oblique _facial clefts_, and their relations to the above.