39 



Volga, and kindly sent to me for examination from the Zool. Museum of 

 St. Petersburg. 



Distribution. Sweden (Lilljeborg), British Isles (Brady), Germany (Schmeil), 

 Turkestan (Uljanin), Mongolia and Mouth of Volga (the present author). 



19. Cyclops insignis, Glaus. 



(PI XXI). 



('//il/>ps insignis, Claus, Weitere Mittheilungen viber Cyclopiden, Arch. Nat. Hist. 23 Jahrg. Bd. 1, 



p. 209, PI. XI, figs. 813. 



Syn. : Cyclops quadricornis, Koch. 



Specific Characters. Female. Body rather slender, though having the 

 anterior division somewhat dilated and of regularly elliptical form, its greatest 

 width somewhat exceeding half the length and occurring in the middle. Lateral 

 parts of penultimate trunk-segment not produced, and of same shape as those of 

 the 2 preceding segments. Last trunk-segment rather broad and sharply pointed 

 on each side. Tail slender and attenuated, though shorter than the anterior 

 division; genital segment very broad in front and abruptly constricted behind. 

 Caudal rami long and slender, considerably exceeding in length the last 3 seg- 

 ments combined, and narrow linear in form, being only very slightly divergent, 

 each ramus exhibiting dorsally a very distinct longitudinal keel; seta of outer 

 edge somewhat remote from the end, apical setae not much elongated, the inner 

 medial one being scarcely more than twice as long as the ramus, seta of inner 

 corner very little longer than that of the outer, which is rather strong, almost 

 spiniform. Anterior antennae of moderate length, reaching, when reflexed, about 

 to the middle of the 2nd segment of the body, and composed of only 14 joints, 

 the 8th to 1 1th joints being coalesced into a single elongate segment. Posterior 

 antennae with the terminal joint scarcely longer than the penultimate one. Nata- 

 tory legs more strongly built than in the preceding species, terminal joint of outer 

 ramus in all of them having only 2 spines outside; outer apical spine of inner 

 ramus in 4th pair less rudimentary, exceeding half the length of the inner. Last 

 pair of legs with the distal joint rather narrow and somewhat constricted near 

 the base, lateral spine of moderate size and attached about in the middle. 

 Ovisacs large, oval, and carried closely appressed to the sides of the tail. Seminal 

 receptacle short and broad, of a somewhat irregular transversely elliptical form 

 and not produced behind. Spermatophores attached to the genital opening placed 

 at right angles to the axis of the body. 



Colour yellowish, with a more or less distinct olivaceous tinge. 



Length of adult female amounting to 2.60 mm. 



