1. An abnormal lobster cheliped is described in this paper. The abnormality consists of a double extra crushing claw arising from the meropodite of a claw of the nipping type.2. The conditions found here are shown to present an exception to Bateson's rules of secondary symmetry.3. The primary member of the so-called triple claw was found to be of the same character as the corresponding appendage of the opposite side, furnishing an exception to the normal condition of asymmetry.4. Pigmentation was reversed in the double extra claw.5. There is some evidence in favor of the view that there is a definite relation between the reversal of pigmentation and the doubling of the extra appendage.