28 BRITISH PARASITIC COPEPODA. 



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

 sitic Copepoda 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, Bomoloclms, and Thersitina. 



The Caligoida. 



The Caligoida are represented by many genera and 

 species ; they are arranged under three families viz., 

 the Caligidas, the Dichelestiidae, and the Philich thy idee. 

 The Caligidas have been divided into the following sub- 

 families : the Caliginae, Trebinaa, Euryphorinae, Pan- 

 darinae, and Cecropinae ; but witli the exception of 

 the Caliginae, 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 Lernsdoida. 



The Lernaeoida also comprise a considerable number 

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

 are arranged under three families viz., the Lernaeidae, 

 the Chondracanthidae, and the Lernaeopodidae. 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. 



