The chondrocranium of the existing specimens of the larval Polypterus have been redescribed, and the earlier specimens figured for the first time. The development of the following structures have not been described previously in Polypterus:
1. The lateral commissure which forms first from the prootic and then the post-palatine process.
2. The taenia marginales, which arise as distinct cartilages.
3. The development of the visceral arches and the temporary fusion of the first and second hypobranchials and ceratobranchials.
This development is then briefly compared with those of Scyllium, Amia, Lepidosteus, Acipenser, and Teleosts; a strong likeness being shown between it and that of Amia. The view of Goodrich is thus afforded additional support.