28 BRITISH PARASITIC COPEPODA. 



Dr. Bassett-Smith in his excellent paper on " Para- 

 sitic Oopepoda found on Fishes," published in 1899,* 

 follows, with some slight modifications, the classifica- 

 tion proposed by Grerstaecker in Bronn's ' Tierreich,' 

 1881, and as Sars' main divisions fit in fairly well with 

 this arrangement it has been retained here. 



The Cyclopoida. 



The Cyclopoida are represented among the Cope- 

 poda parasitic on British fishes by a single family, 

 the Ergasilidse, which comprises the three genera 

 Ergasilus, Bornolochus, and Thersitina. 



The Galigoida. 



The Caligoida are represented by many genera and 

 species ; they are arranged under three families — viz., 

 the Caligidge, the Dichelestiidee, and the Philichthyidse. 

 The Caligidge have been divided into the following sub- 

 families : the Caliginge, Trebinge, Euryphorinse, Pan- 

 daringe, and Cecropinge ; but with the exception of 

 the Caliginge, which comprise Caligus, Lepeophtheirus, 

 and one or two other genera, these subdivisions are 

 each represented by only a small number of species, 

 and it has, therefore, not been considered necessary to 

 adopt these minor divisions here. 



The Lernseoida. 



The Lernseoida also comprise a considerable number 

 of genera and species, and these, like the Caligoida, 

 are arranged under three families — viz., the Lerngeidge, 

 the Chondracanthidge, and the Lernseopodidse. These 

 represent three tolerably distinct types, and exhibit in 

 the adult female a more or less retrograde develop- 

 ment, producing in many cases results, in regard to 



* " A Systematic Description of Parasitic Copepoda found on Fishes, with 

 an Enumeration of the Known Species," in ' Proc. Zool. Soc. London/ 18th 

 April, 1899. 



