228 BIUTISH PAKASITIC COPErODA. 



abdomen ; inner edges proximally contiguous and 

 somewhat divaricate at the distal extremity. An- 

 tennae normal. Sucking-discs of moderate size. Pos- 

 terior maxillipeds tolerably large and stout, their 

 basal plates somewhat expanded posteriorly ; the distal 

 margin of the plates with three short and subequal 

 tooth-like projections. Swimming-legs tolerably elon- 

 gated. Eyes conspicuous. A black mark on each 

 side near the base of the abdomen. Carapace of a 

 greenish colour and ornamented on both sides with 

 darker coloured ramifications. Size of the female 

 about 6 or 7 mm. in length. Male somewhat like the 

 female, but smaller. 



Habitat. Parasitic on various fresh-water fishes, as 

 carp, sticklebacks, trout, pike (Esox luciu*), grey ling 

 (Tliymallus vulgaris), and others. The species appears 

 to be generally distributed throughout the British 

 Islands. Some years ago it was very common on- 

 grey ling in the upper waters of the Clyde, but after a 

 few days' heavy rain which flooded the river the Aryulux 

 had all disappeared. This species has also been obtained 

 on a fish captured in the Faroe Channel by G. IL 

 Fowler. The specimen is now in the British Museum, 

 and we are indebted to Dr. W. T. Caiman for drawing 

 our attention to it and for the loan of it for exami- 

 nation. 



There appears to he some uncertainty as to the relationship 

 between the Argulidse and the species usually recognized as 

 Copepoda. Dr. Baird includes the Family Argulidse in. the 

 same Tribe Peltocephala with the Caligidge, the Pandaridae, 

 and the CecropidaB.* In 1866 Gerstaecker, revising Iris 

 previous classification, replaces the Argulidae under the 

 Branchiopoda.t Glaus in 1875 proposed making the Argulidae- 

 a second suborder of the Branchiura, under the Order Cope- 

 poda. J On the other hand, the Eev. T. R. K. Stebbing, in 

 f A History of Crustacea/ places the carp-lice (Arguhm) in 

 the suborder Branchiura of the Order Branchiopoda, and 



* ' Entomostraca,' p. 15. 



f Q/^Bronn's ' Klassen und Ordnungen des Thierreichs/ vol. v, p. 16. 

 | " Uber die Entwickelung, Organisation, und Systematische Stellun or- 

 der Arguliden," ' Zeitsch. f. wissensch. Zool./ vol. xxv, pp. 217-284, pis. 



xiv-xvm. 



