Abstract
The karyotype of a platyrrhine, Cebus capucinus, is compared with that of man and other catarrhines. It was found that a large degree of analogy of chromosome banding exists among the different species. A common origin for the platyrrhines and the catarrhines can thus be deduced. Furthermore, it becomes possible to reconstruct, to a great extent, the karyotype of the last common ancestor of all of the simians.