Dr. Meijerle[2] has lately described in some detail the {9} particular arrangement of the individual hairs among mammals; they are not by any manner of means scattered without order, but show a definite and regular arrangement, which varies with the animal. For instance, in an American Monkey (_Midas_), the hairs arise in threes--three hairs of equal size springing from the epidermis close together; in the Paca (_Coelogenys_) there are in each group three stout hairs alternating with three slender hairs. In some forms a number of hairs spring from a common point: in the Jerboa (_Dipus_) twelve or thirteen arise from a single hole; in _Ursus arctos_ there is the same general plan, but there is one stout hair and four or five slender ones. There are numerous other complications and modifications, but the facts, although interesting, do not appear to throw any light upon the mutual affinities of the animals. Allied forms may have a very different arrangement, while in forms which have no near relationship the plan may be very similar, as is shown by the examples cited from Dr. Meijerle's paper. The groups of hairs, moreover, have themselves a definite placing, which the same anatomist has compared with the disposition of the bundles of hairs behind and between the scales of the Armadillo, and which has led him to the view that the ancestors of mammals were scaly creatures--a view also supported by Professor Max Weber,[3]and not in itself unreasonable when we consider the numerous points of affinity between the primitive Mammalia and certain extinct forms of reptiles.[4]