CYCLOPS. 



543 



or rather a single cluster of ocelli ; which character, however, it 

 has in common with the two genera already named, as well as 

 with Daphnia ( 368), and 



with many other Entomos- FlG - 276 - 



traca. It contains numer- 

 ous species, some of which 

 belong to fresh water, whilst 

 others are marine. The 

 fresh-water species often 

 abound in the muddiest and 

 most stagnant pools, as well 

 as in the clearest springs ; 

 the ordinary water with 

 which London is supplied, 

 frequently contains large 

 numbers of them. Of the 

 marine species, some are to 

 be found in the localities in 

 which the Cythere is most 

 abundant, whilst others in- 

 habit the open ocean, and 

 must be collected by a fine 

 muslin net. The body of 

 the Cyclops is soft and ge- 

 latinous, and it is composed 

 of two distinct parts, a 

 thorax (Fig. 276, a) and an 

 abdomen (6), of which the 

 latter, being comparatively 

 slender, is commonly considered as a tail, though traversed by 

 the intestine which terminates near its extremity. The head, 

 which coalesces with the thorax, bears one very large pair of an- 

 tennae (c) possessing numerous articulations, and furnished with 

 bristly appendages, and another small pair (d)\ it is also furnished 

 with a pair of " mandibles" or true jaws, and with two pairs of 

 "feet-jaws," of which the hinder pair is the longer, and most 

 abundantly supplied with bristles. The legs (e) are all beset with 

 plumose tufts, as is also the tail (/, /) which is borne at the ex- 

 tremity of the abdomen. On either side of the abdomen of the 

 female, there is often to be seen an egg-capsule or external ova- 

 rium (B), within which the ova, after being fertilized, undergo 

 the earlier stages of their development. The Cyclops is a very 

 active creature, and strikes the water in swimming, not merely 

 with its legs and tail, but also with its antennae. The rapidly 

 repeated movements of its feet-jaws serve to create a whirlpool 

 in the surrounding water, by which minute animals of various 

 kinds, and even its own young, are brought to its mouth to be 

 devoured. 



368. The tribe of Branchiopoda also is divided into two orders ; 



A, female of Cyclops quadricornis : a, body ; 6, 

 tail; c, antenna; d, antennule; e, feet; /, plumose 

 setae of tail : B, tail, with external egg-sacs; c, D, E, 

 F, G, successive stages of development of young. 



