296 HISTORY OF BRITISH CRUSTACEA. 



(and hence the name of the Order, from kcotttj, an oar, and 

 7rof?, a foot). Ovary external. 



Fam. CTCLOPIDM. 



Head and body not distinguishable, being consolidated 

 with the first segment of the thorax. Two pairs of foot-jaws. 

 Five pairs of legs; the fifth pair rudimentary. One eye. 

 The male has a swollen hinge-joint to both antennae. The 

 various species are found in fresh or salt water. Dr. Baird 

 observes, " The fresh-water species abound in the muddiest, 

 most stagnant pools, and in the clearest springs; and the 

 ordinary water, with which the inhabitants of London are 

 supplied for domestic purposes, often contains them in great 

 numbers. The marine species are to be found frequently 

 in immense quantities in small pools on the sea-shore, within 

 high- water mark, living among the seaweeds and corallines 

 which so elegantly fringe the beautiful little wells and clear 

 round pools which are hollowed out in the rocks on the 

 coast, and are to be met with in equal profusion in the open 

 ocean, where, by the curious luminous properties they pos- 

 sess, they assist in producing that beautiful phosphorescent 

 appearance of the sea, the cause of which formerly puzzled 

 naturalists." Jurine has calculated that a single specimen of 



