ANIMAL LIFE IN PONDS & STREAMS 



is the common water flea. By day these animals 

 retire to the mud at the bottom of the pond but, 

 morning and evening, they swim actively with a 

 curious jerky motion. We must examine our spec- 

 men carefully for he is of more than ordinary in- 

 terest. We cannot fail to observe how transparent 

 he is, so much so that all his internal organs can be 

 plainly seen, but let us deal with his exterior first 

 of all. His large eyes are plainly visible, but his 

 most conspicuous feature is the pair of large 

 branched feelers, by means of which he swims. If 

 we examine several specimens, one or more is cer- 

 tain to be a female, then we may probably observe 

 an e^gg in process of formation in the brood pouch, 

 a large, elongated cavity, just below the back of the 

 animal. Immediately above the brood pouch, the 

 heart is situated and, if we can induce its owner to 

 keep still for a moment or two, the heart-beats may 

 be plainly seen. 



Not unlike the water flea as it swims about in 

 the water of our collecting jar is the curious, trans- 

 parent little creature known as Cypris, Although 

 so transparent its body is contained in a pair of 

 shells, very similar to those of the mussel; a fact 

 which formerly led to its being classed with the 

 shell-fish. We may well examine this little fellow 

 under the microscope for much of his structure may 

 be made out through his shell. His very conspicu- 

 ous eye is sure to attract our attention ; he possesses 

 but a single eye and seems to make up for the lack 

 of a second by having a very large one. Two pairs 



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