[None. Introduction starts as:]
The cephalic lobe of the Amphinomidiae, in its most complicated condition, is provided with the following organs: an unpaired antenna, inserted near the posterior border, and two pairs of eyes, one of which is situated in front of, and the other behind, the base of this appendage. A pair of antennae is situated in front of the anterior pair of eyes. On the ventral side, in front of the mouth, are found the two lips, while on the dorsal surface, behind the unpaired antenna, is situated the caruncle. The
external antennae (
auctorum) are tentacular cirri by reason of their innervation, and Quatrefages (1865) justly contends that they must belong to a rudimentary segment.
On studying certain series of forms belonging to the family with which we are dealing, two tendencies may be remarked in the modification of the anterior extremity: (1) The parapodia of the first three or four segments travel more and more towards the front, so that their axes tend to lie in the sagittal plane of the body; (2) the mouth and lips travel more and more towards the rear, and the anterior pair of eyes, with the paired antennae, tends to pass to the ventral surface. It is probable that the second tendency is but a result of the first.