COMPARATIVE ANATOMICAL STUDY OF PROPRIOCEPTORS OF BASI-ISCHIO-MEROPODITE REGION OF WALKING LEG OF SOME DECAPODS (CRUSTACEAN)

1. The crayfish: a) In the meropodite there is a myochordotonal organ (MCO) which is connected with the dorsal muscular bundle of the proximal head of the accessory flexor (AFM). This receptor contains a reduced number of cells in comparison with the crab MCO; however, a secondary group of cells with dendrites which go through the cuticle is also present. b) In the ischiopodite there are two chordotonal receptors: IM 1 near the postaxial wall is sheet-like and attached to the inferior retractor of the meropodite. IM 2 in the anterior part is a thin strand. The ends of the two receptors do not cross the joint and are released by protraction of the meropodite. c) Also described is a new receptor in the basipodite BI. This occurs only in pereiopods 2 to 5 where the B-I joint is well differentiated. 2. Crangon, Eupagurus, Maia, Homarus, Nephrops, Palinurus: All results are compared with previous information about the MCO and other chordotonal organs. It is suggested that as crustaceans evolved the MCO increased in complexity and at the same time the importance of the basi-ischio region became reduced. © 1969 Springer-Verlag.