Fig. 2. Elasmobranch models (A) and ß (B). In A, only every other canal and ampulla system is depicted for presentational clarity. Each canal line forms a vector starting on the modeled elasmobranch's surface and terminating at an ampulla inside the model. Model has one cluster of ampullae; the model measures 20 cm across. Model ß has three separate ampullary clusters spaced 5 cm apart; the model measures 50 cm from side to side and 20 cm from front to back.