In this Pollicipes there is other evidence of concentration in the nervous system, for none of the ganglia show signs of being formed of lateral pairs; the second is close to the first; and the abdominal double chord is in part separated by a mere cleft; lastly, as we shall immediately see, the same remark is applicable to the supra-oesophageal ganglia. The latter (D) alone remain to be described; they present far more diversity in shape than do the thoracic ganglia; they are almost always seen in outline to be laterally distinct, and usually resemble two pears with their tapering ends cut off and united; in a transverse line they are as long as the infra-oesophageal ganglion, but are much less massive. In _Lepas fascicularis_ (D), they are pear-shaped; in _Pollicipes mitella_ they are globular, and separated by a third globular ganglion, which I believe is the ophthalmic ganglion, presently to be described; in _Pollicipes spinosus_, however, the ophthalmic ganglion is, as usual, placed in advance of the supra-oesophageal ganglion, which latter, in this one species, shows no sign of being formed of a lateral pair fused together. In _Alepas cornuta_ the supra-oesophageal ganglion consists of two quite distinct ganglia, elongated in the longitudinal axis of the body, and separated from each other by the whole width of the mouth; the chord which unites them is of the same thickness as the rest of the collar. In all the genera, from the front of each of the two supra-oesophageal ganglia, a pair of nerves, (_f_, _f_,) united and together as large as the collar nerve, rises, and can be traced running unbranched, in a nearly straight line, for a length equalling the whole rest of the nervous chord, so as to supply the peduncle and the inside of the capitulum or sack. At the inner ends of these two same ganglia, from a central point where they are united, a little central branch runs in front to the adductor scutorum and other adjoining muscles; and still smaller fibrils run behind to the oesophageal muscles. [Illustration: Diagram of the anterior portion of the nervous system in _Lepas fascicularis_. A. First thoracic or infra-oesophageal ganglion. B. Second thoracic. C. Third thoracic ganglion. D. Supra-oesophageal ganglion. E. The two ophthalmic ganglia. F. Double eye. _a_. Nerve going to first cirrus; _b_, to the muscles below the first cirrus; _c_, to the second cirrus; _d_, to the third; _e_, nerves running to the ovaria; _f_, double nerves supplying the sack and peduncle.]