Summary.1 In a large number of embryos ofVipern berus, Natrix natrixand other snakes a single median egg‐tooth is present. No evidence for the existence of a second rudimentary egg‐tooth pertaining to the left side of the premaxilla, as was stated to occur by some previous workers, was found.2 In addition to the egg‐tooth a single rudimentary toothlet develops in relation to each half of the premaxilla in embryos of most ophidian species studied. These toothlets are probably resorbed before birth. They represent the remnants of the more extensive premaxillary dentition present throughout life in lizards and in some relatively primitive snakes.3 The condition in embryos ofPython, where teeth are present on the premaxilla throughout life, is described. In one of these embryos a premaxillary tooth on each side possesses a small accessory cone.4 In two embryos ofVípera berusthe egg‐tooth is partly divided into two cones of equal size; the significance of this condition of partial dichotomy is discussed, and is thought unlikely to have phylogenetic significance.5 In most snakes, including both oviparous and ovoviviparous forms, the egg‐tooth is curved so that it projects forwards from the premaxilla. In the ovoviviparousVípera berusandSisturus catenatusthe egg‐tooth points more or less downwards, and is presumably non‐functional. It is suggested that the egg‐tooth may undergo retrogressive changes in some ovoviviparous Squamata, where it has no functional importance.6 The presence of a median premaxillary tooth in a subadult specimen of the snakeIlysiais reported. Comments on the nerve‐supply of median teeth and