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IOWA ACADEMY OF SCIENCE Voi., XXVII, 1920 
Daphnia longispina var. hyalina Eeydig 1860. Great variations in form 
of crest. Deep and surface tows, West Okoboji lake. 
Daphnia longispina var. longiremis Sars 1861. Not abundant. Deeper 
tows on West Okoboji lake. 
Genus Simocephalus Schoedler 1858 
Simocephalus vetulus (O. F. Mueller) 1776. Abundant. Widely dis- 
tributed, present in practically all collections. 
Simocephalus serrnlatus (Koch) 1841. Very abundant. Widely dis- 
tributed. 
Genus Scapholeberis Schoedler 1858 
Scapholeberis mucronata (O. F. Mueller) 1785. Abundant. Drainage 
canal and West Okoboji lake. 
Genus Ceriodaphnia Dana 1853 
C eriodaphnia reticulata (Jurine) 1820. Abundant. Kettle holes and 
drainage canal. 
Ceriodaphnia megalops Sars 1861. Rare. Kettle hole north of Milford. 
Ceriodaphnia quadrangula (O. F. Mueller) 1785. Found with C. meg- 
alops. 
Ceriodaphnia laticaudata P. E. Mueller 1867. Not abundant. Grassy 
kettle holes. 
Genus Moina Baird 1850 
Moina brachinta (Jurine) 1820. Very abundant. Kettle holes, lakes 
and drainage canal. 
Moina affinis Birge 1893. Abundant. A kettle hole species. 
Moina rectirostris (Eeydig) 1860. Muddy kettle holes. 
Family BQSMINIDAB Sars 
Genus Bosmina Baird 1845 
Bosmina longirostris (O. F. Mueller) 1785. Very abundant everywhere. 
Family MACROTHRICIDAB Norman and Brady 
Genus Bunops Birge 1893 
Bunops serricaudata (Daday) 1888. Rare. Outlet of Center lake near 
Hayward’s bay. 
Genus Ilyocrypius Sars 1861 
Ilyocryptus sordidus (Eievel) 1848. 
Ilyocryptus spinifer Herrick 1884. Both species abundant. Kettle holes. 
Genus Macrothrix Baird 1843 
Macrothrix laticornis (Jurine) 1820. 
Macrothrix rosea (Jurine) 1820. 
Macrothrix rosea var. tenuicornis Kurz. Abundant in kettle holes and 
canal. M. rosea most abundant and widely distributed. 
Family CHYDORIDAB Stebbing 
Genus Burycercus Baird 1843 
Burycercus lamellatus (O. F. Mueller) 1785. Common. Drainage canal 
and kettle holes. 
