228 BRITISH PAEASITIC COPEPODA. 



abdomen ; inner edges proximally contiguous and 

 somewhat divaricate at the distal extremity. An- 

 tennas 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 lucins), greyling 

 (Thymallus vulgaris), and others. The species appears 

 to be generally distributed throughout the British 

 Islands. Some years ago it was very common on 

 greyling in the upper waters of the Clyde, but after a 

 few days' heavy rain which flooded the river the Arguhis 

 had all disappeared. This species has also been obtained 

 on a fish captured in the Faroe Channel by Gr. H. 

 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 be some uncertainty as to the relationship 

 between the Argulidee and the species usually recognized as 

 Copepoda. Dr. Baird includes the Family Argulidse in the 

 same Tribe — Peltocephala — with the Caligidse, the Pandaridse, 

 and the Cecropidas* In 1866 Gerstaeeker, revising his 

 previous classification, replaces the Argulidas under the 

 Branchiopoda.f Claus in 1875 proposed making the Argulidas 

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

 poda. X On the other hand, the Rev. T. H. E,. Stehbing, in 

 'A History of Crustacea/ places the carp-lice (Arguhis) in 

 the suborder Branchiura of the Order Branchiopoda, and 



* ' Entomostraca/ p. 15. 



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



% " t)ber die Entwickelung, Organisation, und Systematische Stellung 

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

 xiv-xviii. 



