On the other hand, we cannot refuse to admit that any of the processes of an Arthropod parapodium may become modified as branchial organs, and that, as a rule, branchial out-growths are easily developed, de novo, in all the higher groups of animals.
A common modification of the chief ramus of the Arthropod parapodium is the chela or nipper formed by the elongation of the penultimate joint of the ramus, so that the last joint works on it FIG.
The notopodium may be rudimentary or absent and the entire parapodium reduced to the merest ridge or even completely unrepresented.
When the animal is turned on its left-hand side and the mantlechamber widely opened, the gill being turned over to the left, a part of the kidney is seen beneath the skin between the attachment of the gill and the right parapodium (fig.
The most extreme disguise assumed by the Arthropod parapodium or appendage is that of becoming a mere stalk supporting an eye - a fact which did not obtain general credence until the experiments of Herbst in 1895, who found, on cutting off the eye-stalk of Palaemon, that a jointed antenna-like appendage was regenerated in its place.
The parapodium is represented with its neural or ventral surface uppermost.
The principal forms assumed by the Arthropod parapodium and its rami may be thus enumerated: (1) Axial corm well developed, unsegmented or with two to four segments; lateral endites and exites (rami) numerous and of various lengths (certain 8 limbs of lower After Lankester, Q.