III.—The Development of the Skull and Visceral Arches in Lepidosiren and Protopterus

Abstract

The material for this work was that collected and prepared by Professor J. Graham Kerr in the Chaco (Lepidosiren), and by Budgett from the Gambia (Protopterus). The process of development follows nearly the same course in the two genera, and where differences occur they are mainly such as are to be expected from a comparison of the adult skulls. While the series of stages of Lepidosiren left no unfilled gaps, the material was scantier in the case of Protopterus. Except where otherwise stated, the detailed descriptions were worked out in Lepidosiren, but whenever I was unable to verify that the process was substantially the same in the other genus, the fact has been mentioned. The stages are numbered in correspondence with the stages figured by Graham Kerr (Phil. Trans. Roy. Soc, B., vol. cxcii.). The Protopterus stages are numbered the same as the corresponding ones in the other genus. As far as possible, the nomenclature adopted by Gaupp* has been adhered to.