Finger-prints of Twins.-A study of the fingerprints of twins has been made by Prof. H. H. Newman (Jour. Genet., vol. 23, No. 3). The material consisted of the prints of 100 pairs of same-sexed twins, 50 of whom were classed as identical and 50 as di-zygotic or fraternal. He regards the whorl as the most primitive pattern, while some have given this place to the loop, which occurs in primitive form in anthropoids. He finds that the finger-prints of identical twins may be extraordinarily alike in pattern, although they always differ in minutiae. The distribution of whorls, loops, and arches is the same in both types of twins and agrees with that of the general population. Radial loops and radial whorls are largely confined to the index finger. This is interpreted as a result of the early dichotomy of the limb bud, separating the thumb primordium from the rest of the fingers and tending to produce in the index finger a pattern the reverse of that in the thumb. Tented arches, which are common on forefingers, are interpreted as cases of partial asymmetry reversal. In identical twins the patterns on one or both hands resemble the hands of the other twin more strongly than do opposite hands of the same individual. The reverse is true of fraternal twins, and this difference can be used as a criterion for classifying doubtful twin pairs. If the finger patterns in human twins are compared with the scale patterns in armadillos, it is found that in both man and the armadillo parallel-imaging is about twice as frequent as mirror-imaging of asymmetrical peculiarities. This leads to the conclusion that monozygotic twins in man arise in the same general way as the quadruplets which normally occur in the armadillo, that is, by a process of budding in the early embryo.