OBSERVATIONS ON THE ARGULUS FOLIACEUS, (Jurine), 



AS INJURIOUS TO GOLD AND SILVER FISHES. 



By Miss Dobson. — (Communicated by Mr. George Samouelle). 



Genus 85. Argulus, Miill., Jurine, Leach, Desmarest, Samouelle ; 

 Binoculus, Geoffroy, Latreille. 



Shell oval, somewhat membranaceous, semi-transparent, anteriorly rounded, 

 deeply notched behind : two hemispheric eyes inserted at the anterior and lateral 

 parts of the clypeus : antenna; very small, inserted above the eyes : rostellum 

 sterniform : twelve legs, unequal in size and form ; first pair shorter, very mem- 

 branaceous, capable of changing their form, broader at their tips, and constructed 

 for adhering to objects ; second pair prehensile, curved, much thicker towards 

 their base, the thighs furnished with three spinules beneath ; tarsi of the second 

 pair three-jointed, the last joint with two claws and a pulvillus ; four hinder pairs 

 inserted at the sides of the abdomen, somewhat cylindric, formed for swimming, 

 with their points bifid : abdomen cylindric ; tail bilobate. 



Sp. 1. Arg. foliaceus, Jurine. 



Argulus delphinus, Miill., Enton., 123. Monoculus Argulus, Fabr., Ent. 

 Syst., 489. Argulus foliaceus, Leach, Suppl. to Encycl. Brit., p. 405. ; 

 Desmarest, Considerations des Crust., p. 329, pi. 50, fig. 1, a. e. 



