The defects of enamel hypoplasia can be related to the layered structure of enamel which represents the sequence of development in tooth crowns. From such studies, it is possible to see that furrow-type enamel defects (the most common form of hypoplasia seen with the naked eye) are just the most prominent expression of a continuum which extends ever smaller, down to a microscopic disturbance to a single layer in the crown formation sequence. Furthermore, the progressive decrease in spacing between development layers which occurs down the crown sides, from occlusal to cervical, affects both the prominence and apparent width of the defects. This makes it difficult to use measurements as a means of estimating the duration of the disturbance causing a particular defect. The difficulty is even greater for the less common pitted or exposed-plane-type defects, for which the apparent width bears very little relationship with the duration of the growth disturbance. The defects of enamel hypoplasia can therefore be understood clearly only when examined under the microscope in relation to the structures which mark the development sequence of the tooth crown.

Diagnosis of the congenital form of syphilis is an important part of the palaeopathology of this disease. In theory, there are clear clinical signs to be found in the long bones and teeth, but it has rarely been possible to recognise the latter with a confidence in archaeological material, partly because the original descriptions of the dental deformities are sometimes contradictory and partly because it is nowadays difficult to find reference specimens in museums. This article describes two such specimens which have recently been rediscovered, and discusses the form of the dental defects which they show (Hutchinson's incisors, Moon's molars, and mulberry molars) in relation to the developmental sequence of the teeth.

No abstract

No abstract

The mammal collections of the San Diego Society of Natural History comprise more than 21,000 specimens, of which the majority are from the southwestern United States and Baja California, Mexico. Included are holotypes of two species and 87 subspecies. In this catalog Of type specimens, the following information is given: name as originally published, original citation, currently accepted name if different from the original, collector, date of collection, original number, museum number, and type locality. Unless otherwise specified, all taxa listed here were considered valid by Hall and Kelson (Mammals of North America.