THE FISHES, MOLLUSCA, AND OTHER OBJECTS. 53 



transparent as if they had been made out of spun 

 glass. Those of the males are thicker and shorter, 

 swelling towards the tips. By means of the antennae, 

 therefore, the student will not find it difficult to 

 distinguish the sexes (Fig. 47). In its progress 

 through the water, the cyclops moves with a rapid 

 jerking motion, which may be best seen in a 

 bottle when it is between the eye and the light. 

 Its principal propelling organs are five pairs of 

 oar-like feet ; each foot consists of a common stem, 

 from which spring two jointed branches, liberally 

 supplied with short, bristly appendages, called seise. 

 The female cyclops may, in July, be further distin- 

 guished from the male by its external ovaries, which 

 hang suspended from either side the end of the body 

 like bunches of grapes (Fig. 49). So abundantly 

 do these creatures multiply, if left undisturbed, 

 that it has been calculated one female, in the course 

 of a year, would become the progenitor of nearly 

 four millions and a quarter of young ! Nothing can 

 be more unlike the parent cyclops than the young, 

 as may be seen by Fig. 48 ; and indeed, for a long 

 time it was classed by naturalists as a distinct genus. 

 It is only by repeated moulting that it eventually 

 attains the parental resemblance. The water-fleas 

 and cyclops are, without doubt, the staple food, not 

 only of fishes, but of other aquatic creatures as well 

 an end for which their marvellous powers of re- 

 production remarkably fit them. 



In such places as these tarns, it will be next to 



