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BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



MICROCTCLOPS VARICANS (G. O. Sars) 



Figure 194 



Cpclotps varicans Sars, Forh. Vid.-Selsk. Christiania, 1862, p. 252 ; Crustacea of 



Norway, vol. 6, p. 54, pi. 33, 1913. 

 Microcyclops varicans Kiefek, Das Tierreicli, Lief. 53, p. 86, 1929. 



Occurrence. — Both sexes found in abundance in three of the 

 brackish ponds on Chappaquiddick Island and in Poucha Pond on 

 the other side of the same island; in Quisset and Crockers Ponds, 

 Falmouth, and in Farm Pond, Marthas Vineyard. 



Distribution. — Norway (Sars) ; Sweden (Lilljeborg) ; Germany 

 (Schmeil) ; Turkestan (van Douwe, Uljanin) ; Poland (Lande) ; 



Africa, New Zealand (Sars) ; 

 Lake Albert Nyanza (Cun- 

 nington) ; British Isles (Scour- 

 field) ; Russia (Matile) ; Scot- 

 tish Lakes (T. Scott) ; Swit- 

 zerland (Graeter) ; Illinois 

 River (E. B. Forbes) ; Nan- 

 tucket Island (Pearse). 



Color. — Body transparent, 

 anterior portion colorless, but 

 the longitudinal muscles are 

 pale yellow and the digestive 

 tract is reddish, posterior por- 

 tion yellow, the digestive tract 

 again reddish. Eye ruby red, 

 the lenses colorless and scintil- 

 lating ; eggs pale bluish green, 

 the color persisting in forma- 

 lin. 



Female. — Metasorae oval, a little more than half as wide as long, 

 the fifth segment produced a little laterally ; urosome more than half 

 as long as the metasome; genital segment widened anteriorly, nar- 

 rowed posteriorly; caudal rami as long as the last two abdominal 

 segments, outer seta somewhat removed from the tip of the ramus. 

 First antennae 12-segmented, not so long as the cephalic segment; 

 rami of first four pairs of legs 2-segmented, spines and setae on the 

 end segment of the exopods as follows : 3, 5 ; 4, 5 ; 4, 5 ; 3, 5. Basal 

 segment of fifth leg fused with the fifth metasome segment, its pres- 

 ence indicated by a plumose seta ; rarely the segment is distinctly sep- 

 arated. Distal segment small and conical with a single apical seta. 

 Seminal receptacle small, longitudinally elliptical in the center, con- 

 tracted into a narrow band on either side. Total length, 0.7-0.9 mm. 



FiGCEE 194. — Microcyclops varicans: a, Malp, 

 dorsal ; 1), male, first antenna ; c, male, fifth 

 and sixtb legs ; d, female, fifth leg (variant) 



