lour, which produce an admirable contrast with the green colour of the body, which is a little transparent and spotted with brown rays, artfully arranged. Quelles decouvertes ne doit on pas espérer de faire désormais dans l'Histoire Naturelle, puisq' on trouve des poissons avec des plumes!"—p. 275.
Cyclopsina Slabberi, Baird. Body oval. Tail short. Antennae long, shorter than in the last species, about the length of the whole insect; numerously articulated and provided with rather long and numerous setae. The last articulation of tail is bifurcated, each division being furnished with five short stout setæ, which are not plumose.-— The ova, in the specimen figured in my Journal, appear lying across the centre of the body instead of the tail, as in the Cyclopsina Castor, &c, and I have noticed this peculiarity in my notes at the time.
Inhabits the Southern Indian Ocean. "July 20, 1832, in lat. 11° 36' S. long. 105° 39' W. The water this evening was still more luminous than last night. Upon drawing up a bucket-full from alongside, and leaving it at rest for a short time, several beautiful bright spots or bodies might be distinctly seen floating in it, and at times darting through the water with great rapidity. Upon examination in the morning, I found four different kinds of animalcules in it, of which two were species of Cyclops. There is no doubt these were the luminous bodies seen in the water, and which were observed darting through it at such a rate."—Private Journal.
Slabber, in his work upon the microscope,[1] gives a figure of a "Zeewater luis," which very much resembles this species, (see p. 52, t. 17, fig. 3). He represents it with two eyes, and makes body and tail in one, but the antennae and caudal filaments, together with the general form of the animal, leaves no doubt in my mind as to the identity of the two insects: I have therefore named it after him as its first observer.
Genus.—Oithona,[2] Baird.
This genus is distinguished from Cyclopsina, by having a pair of short antennae situated immediately in front of the long pair. The antennules, as in the last genus, are divided into two branches.
Oithona plumifera, Baird. This is a very beautiful species, but very minute in size. The body is rather slender, oval, and of an elegant appearance. Tail elongated and slender. The long antennae are fully the length of the whole insect, numerously articulated and cili-
