8 Trans. Acad. Sci. of St. Louis 



GENUS PLEUROXUS BAIRD 1843. 

 9. PLEUROXUS DENTICULATUS. Birge, 1877. 



Pleuroxiis denticulatus, Birge, '76. pp. 20, 21. pi. 1, fig. 21. 

 Pleuroxus denticulatus, Herrick & Turner, '95. p. 256. pi. 45, fig. 

 8 ; pi. 63, fig. 10a, 12, 13. 

 Common in marshes and among vegetation, in no-outlet ponds and lakes 

 of this district. Collected from water with temperature ranging from 

 18-31°C. The hydrogen ion content of the water was calculated only once, 

 when it was found to be PH 8.2. 



10. PLEUROXUS HAMULATUS Birge 1910. 



Pleuroxus humatus, Birge, '76. pp. 22, 23. pi. 2, fig. 13, 14. 



Pleuroxus hamatus, Herrick & Turner, '95. p. 257. pi. 60, fig. 1. 

 This species which heretofore has not been found outside of New England 

 and the Southern States, has been collected from three different no-outlet 

 ponds of this district. In one case the pond was weedy and this species 

 seemed to be dominant ; in the other cases the water was free from any 

 vegetation higher than algae. In two cases the water was comparatively 

 fresh ; in the third it had a disagreeable stench. The temperature and 

 hydrogen ion content of the water were determined in only one case, the 

 temperature being 32°C, the PH 7.4. 



FAMILY DAPHNIDAE 

 GENUS CERIODAPHNIA DANA 1853 



11. CERIODAPHNIA LACUSTRIS Birge 1893. 



Ceriodaphnia lacustris, Birge, '18. p. 701. fig. 1083. 

 Found in this district in a large reservoir furnishing water for the 

 Wabash railroad. The temperature of the water was 27 ^C, the hydrogen 

 ion content PH 8.2. 



12. CERIODAPHNIA DATICAUDATA P. E. Mueller 1867. 



Ceriodaphnia laticaudata, Herrick & Turner, '95. p. 171. pi. 41, 



fig. 22. 

 Ceriodaphnia consors, Herrick & Turner, '95. pp 171, 172. pi. 42. 

 fig. 4 ; pi. 44, fig. 5, 6. 

 Collected twice in this district, each time from a temporary pond, once 

 in June, 1910, when it was abundant, and again in June, 1920, when it was 

 rare. 



13. CERIODAPHNIA PULCHELLA Sars 1862. 



Ceriodaphnia pulchella, Herrick & Turner, '95. p. 169. pi. 41, fig. 



14, 19. 



Collected in this district among water plantain in a lake. 



14. CERIODAPHNIA RECTICULATA (Jurine) 1820. 



Ceriodaphnia reticulata, Herrick & Turner, '95. p. 170. pi. 41, fig. 



15, 21 ; pi. 42, fig. 3 ; pi. 43, fig. 3 ; pi. 44. fig. 3. 4. 



This species was found in a no-outlet pond in March and in November, 

 1909. 



15. CERIODAPHNIA RIGAUDI Richard 1894. 



Ceriodaphnia ripuadi, Birge, '18. p. 700, fig. 1078. 

 Collected July 21, 1921, from a no-outlet pond the temperature of which 

 was 29°C. and the PH value 7.8. August 1, 1921, it was collected from a 

 marsh having a temperature of 25 °C. and a PH value of 7.8. On each oc- 

 casion some of the females were carrying winter eggs. To the best of my 

 knowledge this is the first time this species has been reported from this part 

 of the country. 



GENUS DAPHNIA O. F. MUELLER 1785 



16. DAPHNIA LONGISPINA (O. F. Mueller) 1785. 



Daphnia longispina, Herrick & Turner, '95. p. 199. 

 A form which seems to be the typical form of this species, found in a 

 large reservoir having a temperature of 27°C. and a PH value of 8.2. 

 Although it was May, some of the females were carrying winter eggs. 



