at early metamorphosis (legs 12 mm. long), the synotic tectum extends farther forward (fig. 1 C). The frontoparietals have grown backward partly over the cartilage, and also reach forward to the anterior end of the cerebral hemispheres. At this stage each frontoparietal shows an adjustment of its shape to that of the brain (fig. 1 D). The posterior third is slightly convex, fitting over the optic lobe, and the anterior half likewise bulges upward a trifle, over the cerebral hemisphere. This apparently accounts for Parker's mistake, since when light reflects from the wet surface of these bones during dissection it looks as if each were formed of two separate pieces, of the same proportions as shown in his figure. The present work does not establish the real homology of the single pair of existing bones. That probably cannot be done until fossil ancestors of existing Salientia are discovered which show either the loss of parietals, the loss of frontals, or an ancient fusion of the two which took place so early that there is no longer any sign of its occurrence in ontogeny. Until then it may be as well to continue using the familiar term "frontoparietal," remembering that it has no justification in development.' Professor Robert Broom, the South African paleontologist, suggested this inquiry in a lecture during his 1937 visit to the United States, and credit for the idea should consequently be his.