Ill 



BRANCHIURA ARGULIDAE 



77 



position. They are ectoparasites upon various species of fish, 

 Arg-tilus foliaceus being common in the fresh waters of Europe, 

 infesting the branchial chamber or the skin of fresh-water fish, 

 but being frequently taken swimming freely in the water. 



FIG. 48. Argulus foliact'us, young <J , x 15. a 1 , 2 , First and second antennae ; /'. 

 abdonu'ii, /-', compound eye ; /, liver ; in, mandililes ;ind first maxillae ; mx, sei n d 

 maxilla (the median eye is si-en U-tween the two .second maxillae'i ; n/.i-/>, maxilli- 

 pede ; S.g, shell -.^land ; *j>, spine; (, te.stis ; 1, 4, first and fourth swimmin- 

 appendages. (After Clans.) 



Both males and females can swim with great agility, and tht-y 

 leave their hosts regularly at the breeding season in spring and 

 autumn; fertilisation is internal, and the I'mnili- deposits tin- 

 eggs on stones and other objects. Al'lt-r leaving its host, an 

 Arynlus, if it cannot find a. fish of the same species, can live 

 on almost any other species, and may even attack Frog tadpoles; 

 while the kinds that infest migratory fish can change with tln-ir 



