BRANCHIURA ^ARGULIDAE 



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position. They are ectoparasites upon various species of fish, 

 Argidus foliaceus being common in the fresh waters of Europe, 

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



but being frequently taken 



freely in the water. 



FlO. 48. — Argulus foliacms, young i, x 15. a}, a\ First and second antennae ; ah, 

 abdomen, E, compound eye ; I, liver ; m, mandibles and first maxillae ; mx, second 

 maxilla (the median eye is seen between the two second maxillae) ; mxp, maxilli- 

 pede ; s.g, shell-gland ; sp, spine ; t, testis ; 1, 4, first and fourth swimming 

 appendages. (After Clans.) 



Both males and females can swim with great agility, and they 

 leave their hosts regularly at the breeding season in spring and 

 autumn; fertilisation is internal, and the female deposits the 

 eggs on stones and other objects. After leaving its host, an 

 Argulus, 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 their 



