_Ophthalmic Ganglia and Eyes._--Owing to Professor Leidy’s[16] discovery of eyes in a Balanus, I was led to look for them in the Lepadidæ. Extending from the front of the two supra-oesophageal ganglia, two chords may be seen in _Lepas fascicularis_ (of which a rude diagram is here given), to run into two small, perfectly distinct oval ganglia (E), which are not united by any transverse commissure. From the opposite ends of these two ganglia smaller nerves run, and, bending inwards at right angles, enter, beyond the middle, an elongated (F), almost black, eye, composed of two eyes united together. Although in outline the eye appears single, two lenses can be distinctly seen at the end, directed upwards and towards the ganglia; two pigment-capsules can also be distinguished; these are deep and cup-formed, and of a dark reddish-purple. The following measurements will show the proportions of the parts in a specimen of the _Lepas fascicularis_ having a capitulum 4/10ths of an inch in length. Double eye { length 26/6000 { width 13/6000 Diameter of single lens 6/6000 Ophthalmic ganglion { length 16/6000 { breadth 11/6000 Supra-oesophageal ganglion, } transverse or longest axis } 126/6000 of both together } Supra-oesophageal ganglion, } longitudinal axis of } 45/6000 Infra-oesophageal ganglion, } transverse axis of } 120/6000 Infra-oesophageal ganglion, } longitudinal axis of } 114/6000 [16] Proceedings of the Academy of Natural Sciences, Philadelphia. No. i, vol. iv, Jan. 1848.