CLADOCERA OF THE OKOBOJI REGION 
FRANK A. STROM STEN 
# The following list of Cladocera is a continuation of the list 
published in the Proceedings of the Iowa Academy of Science 
for 1917. It represents the species collected during the summer 
of 1919, from June 24 to September 1.* 
PHYLUM: ARTHROPODA 
Class : Crustacea 
SUB-CLASS : ENTOMOSTRACA 
Order: CLADOCERA 
FAMILY: SJDIDAB 
Genus Sida Straus 1820 
Sida crystallina (O. F. Mueller) 1785. Abundant throughout the season. 
Widely distributed in kettle holes and lake. A tow taken off the end of 
the laboratory dock at night above a sunken electric light was especially 
rich in Sida. 
Genus Diaphanosoma Fisher 1850 
Diaphanosoma leuchtenbergianum Fisher 1850. Not abundant. Found 
late in the season from surface tows taken on West Okoboji lake after 
a heavy rain and strong wind. 
Genus Psendosida Herrick 1884 
Pseudosida bidentata Herrick 1884. Rare. Few specimens found in lake 
tow on August 23. 
Genus Latonopsis Sars 1888 
Latonopsis occidentalis Birge 1891. Not abundant. West Okoboji lake, 
August 2. 
Family DAPHNIDAB Straus 1820 
Genus Daphnia O. F. Mueller 1785 
Daphnia pulex var. pulicaria Forbes. Abundant in kettle holes and 
lake during July. 
Daphnia retrocurva Forbes 1882. Most abundant species of Daphnia 
found in lake tows during July and August. 
Daphnia longispina proper (O. F. Mueller) 1785. Abundant in lake 
tows. 
* For descriptions and figures of species see Ward and Whipple, Fresh-Water 
Biology, pp. 676-739, 1918. Herrick, C. L*, Synopsis of the Fntomostraca of Minne- 
sota: Second Report of State Zoologist, pp. 145-276, 1895. 
