98 BRITISH COPEPODA. 



As regards discrimination of species the genus 

 Cyclops is perhaps the most difficult and puzzling of 

 all the Copepoda. The rough characters dependant 

 on colouring and conspicuous structural peculiarities, 

 such as are in many groups appreciable with the help 

 of an ordinary pocket lens, are here either absent, or so 

 subject to variation as to be of small use as critical 

 marks, while the numerous examples in various 

 stages of development which are always met with in a 

 copious gathering of Cyclopidae constitute a source of 

 constant confusion. The only safe rule in this state 

 of things is to accept no specimens as types which do 

 not show amongst them ova-bearing females. I do not 

 at all believe that the fourteen species described in this 

 book are all, or nearly all, of what will be ultimately 

 recognised as British. It is impossible to think that 

 this number can represent the complete Cyclopid 

 Fauna of Britain, while Gr. 0. Sars has described 

 twenty-seven fresh-water species from Norway. Dr. 

 Anton Fric has, however, described only ten species 

 from Bohemia, Dr. Glaus thirteen from Germany, and 

 Uljanin fourteen from Turkestan. Heller also has 

 noted ten species from Tyrol, some of which (G. Glausii 

 and C. Gredleri] he considers to be new. The specific 

 name Clausii, however, cannot stand, having been 

 applied years ago by Sir John Lubbock to a British 

 species. 



The genus appears to be confined entirely to fresh 

 or to fresh and brackish water, and it is probable that 

 the few marine forms which have been described 

 by various authors as species of Cyclops will, on 



