Stalk of caudal or tail fin, (Measurements 1 ) in Mormyridae part of tail with parallel running dorsal and ventral contours, measured between last ray of either dorsal or anal fin, depending on which one extends most posteriorly, and forking point between the two lobes of the caudal fin, which in this family always are clearly separated. Its length and depth are often specific characters, at least of the various genera. The caudal peduncle harbours the Electric organ, and as a further peculiarity is stiffened by each a dorsal and ventral pair of slender bones, the Gemmingers bones. The colour of the caudal peduncle (in preserved specimens) is often indicated as darker than the rest of the body. This coloration corresponds to the length of the electric organ and may be caused by leaking out of some contents of that organ, so it is an artefact and not seen in live animals, where it may be brighter than its surroundings. In museum specimens the caudal peduncle very often is somewhat translucent which allows to make measurements of the electric organ without dissection.