An Abnormality found in the Cheliped of Macrophthalmus japonicus DE HAAN

Abstract

An abnormality was found in the left cheliped of a female of Macroph-thalmus japonicus DE HAAN obtained at the mud-flats of Hiragata Bay in Yokosuka, Harbour, 1961. The abnormal cheliped is apparently smaller in size and lighter in colour than in the normal right cheliped. In this abnormal cheliped the immovable finger is rather normal in size and shape; at the base of this segment, a process of a good size is projecting at an angle of about 70°. This process looks like an appearance of the movable finger, however it has no articulation at the base; moreover, a small chela-like structure may be found at the proximal portion of the propodus, the chela being rather normal in structure and the movable finger is freely articulated against the immovable finger. These four finger-1ike processes (the original immoval finger, the dectylus-like process and the two fingers on the processes at the base) are found on the same plane, thus this abnormality seems to agree with Bateson's "super-regeneration".