Insects. 



57 



mose setae at the end of the antennae, the fine cilia of which he says 

 are perpetually in motion, but he does not mention the finely plumose 

 filaments of the tail : the second pair of antennae he describes as feet. 

 Mr. T. observes that the fin-legs could not be well made out, on ac- 

 count of the minuteness of the animal, but that they appeared pretty 

 numerous. 



Cyclopsina Arietis. The short line shows the natural size. The detached figure represents an abdominal leg. 



Inhabits the Atlantic Ocean. I first met with it in lat. 12° 38' N. 

 long. 20" 14' W. on the 21st of May, 1832; and again off the Cape of 

 Good Hope, in lat. 35° 29' S. long. 21° 50' E. when I noticed the male 

 also, which is distinguishable by the swelling and large joint of the 

 right antenna. During the previous night the sea was luminous. 



The genus Cyclopsina is constituted by Milne Edwards, to receive 

 those species of the genus Cyclops of Muller, which have the second 

 pair of antennae divided into two branches. The type of the genus is 

 the Cyclops rubens of Muller, the Monoculus Castor of Jurine. The 

 genus Calanus was established by Leach, to receive those species 

 which had no second or posterior pair of antennae, and had the ante- 

 rior ones very long. The type of this genus is the Monoculus finmar- 

 chicus of Gunner. On reference however to the figure of this species 

 given by Gunner, in the Kiobenhavn. Selsk. tom. x. p. 175, fig. 20 — 

 23, it appears that a second pair of antennae do exist in it, and as they 

 are found in all the other species resembling it, it is evident that the 

 genus Calanus, as constituted by Leach, cannot stand. I have there- 

 fore preferred the genus formed by Milne Edwards. 



