Fig. (6) Brain diagrams of four different radiations of cartilaginous fishes, dorsal aspect: A) a holocephalus (Callorhinchus millii); B) a squalomorph shark (Squalus acanthias) [7]; C) a galeomorph shark (Carcharinus leucas) [10]; D) and the brain of a myliobatiform ray (Myliobatis californica). E) Basking shark (Cetorhinus maximus) [47] brain is presented, as of a large bodied plankton feeder such as Mobulids. Brains are not to scale. For comparison see Fig. (2A, B) for M. japanica brain.