62 



Occurrence. I have met with this species not unfrequently in the lake 

 Vansj0 near Moss, where it lives as a true limnetic form. I have also found it 

 occasionally in wide expanses of the river Glommen, at Nipen. 



Distribution. Sweden (Lilljeborg), Germany (Schmeil), Poland (Lande), 

 France (Richard), Russia (Fischer), Cape of Good Hope (G. 0. Sars). 



36. Mesocyelops Dybowskyi (Lande). 



(PI. XXXVIII). 



Cyclops Dijboicskyi, A. Lande, Materyaly do Fauny Scorupiakow Widlonogish, Copepoda. p. 57, 



PI. XVII, figs. 5159. 



Syn: Ci/clops crassus, Lilljeborg (not Fischer). 



Specific Characters. Female. Body somewhat less robust than in M. 

 crassus, with the anterior division regularly oval in outline, greatest width about 

 half the length and occurring somewhat in front of the middle. Last trunk- 

 segment about as in the preceding species. Tail considerably exceeding half the 

 length of the anterior division ; genital segment about the length of the 3 suc- 

 ceeding ones combined, and gradually tapered behind. Caudal rami more pro- 

 duced than in M. crassus, considerably exceeding in length the anal segment, 

 and only slightly divergent; seta of outer edge comparatively small and attached 

 at a short distance from the end; apical setae not much elongated, the inner 

 mediate one not nearly attaining the length of the tail; seta of inner corner 

 much shorter than in the 3 preceding species, being only slightly longer than 

 that of the outer corner and scarcely half as long as the outer mediate one, 

 dorsal bristle not particularly slender. Anterior antennae of moderate length, 

 reaching, when reflexed, about to the end of the 2nd segment. Posterior antennae 

 and maxillipeds about as in M. crassus. Natatory legs also on the whole rather 

 similar; apical spines of inner ramus in 4th pair, however, distinctly different, 

 the outer spine being considerably larger than the inner. Last pair of legs 

 with the distal joint comparatively thicker than in the other species and having 

 the apical setse rather short. Ovisacs of moderate size, oval in shape, and rather 

 divergent. Seminal receptacle with the anterior lobes distinctly recurved. Sper- 

 matophores attached to the genital opening narrow oblong in form and diverging 

 obliquely behind. 



Colour rather peculiar, the body being, as a rule, tinged with a dark 

 bluish or brownish violet hue. 



Length of adult female about 0.90 mm. 



Remarks. This form, first described by A. Lande under the above 

 specific name, has been erroneously identified by Lilljeborg with Cyclops crassus 



