Dictionary of Ichthyology  

Lorenzini's ampullae = the mucus filled canal system opening on the snout of Elasmobranchii, Polyodon spathula and Plotosus anguillaris. May be electric, pressure or temperature receptors.

Wikimedia Commons: http://commons.wikimedia.org/wiki/File:Electroreceptors_in_a_sharks_head.svg

©Canadian Museum of Nature
www.briancoad.com