114 CRUSTACEA. 



abound in fresh and standing waters, are seldom more than 

 one-eighth of an inch long, and may constantly be observed 

 jerking about by the assistance of their long tails. In their 

 forms they somewhat resemble a lobster in miniature, the 

 thoracic part of the body being of an oval form, furnished 

 with a single eye in front (whence the generic name of the 

 group). This part of the body is divided at its hinder part 

 into several segments, which are succeeded by an articulated 

 tail or abdomen, from the base of which in the females de- 

 pends on each side a large membranous bag containing the 

 eggs. 



From their curious forms, great agility, and odd motions, these 

 Uttle insects form conspicuous objects in the exhibitions of the 

 solar microscope. The upper and longer antennae perform the 

 offices of legs, and the lower pair of these organs, from their be- 

 ing kept in a continual rapid motion, produce a kind of whirlpool, 

 which brings into its vortex the minute particles upon which they 

 feed. At the period of couphng the males are extremely active. 

 The eggs, which are of a brown, blue, or green colour, varying- 

 according to their age, become transparent when nearly ready to 

 produce the young ; and it is an extremely curious circumstance, 

 which has been well confirmed, that a single act of impregnation 

 is sufficient for several successive generations. A female cyclops 

 in the space of three months gives birth to not less than ten dis- 

 tinct broods ; and if we calculate only eight broods, each having 

 only forty young, it \n\\ be seen how immense must be the in- 

 crease of these creatures. Muller, the celebrated Danish writer 

 upon these and other alHed animals, not knowing them to be the 

 young of the cyclops, formed them into a distinct genus, v^ith 

 the name of Amymone. Shortly afterwards they acquire an ad- 

 ditional pair of legs, and these for the same reason were formed 

 by the same author into the genus Nauplius. After the first shed- 

 ding of their skin they are said to possess all the organs of their 

 perfect form, but of a diminished size, especially as regards the 

 antennae and legs ; and that after the third moulting they become 

 adult ; but in this manner of reckoning it will follow, that two 

 pairs of legs must be developed \^ithout a corresponding moulting 

 having taken place ; and this is so contrary to what is observed 

 amongst the invertebrated animals, that the correctness of such 

 observation may perhaps he questioned. The chief food of these 

 animals consists of minute particles of animal matter floating in the 



