2 University of Michigan 



which crosses the end of this basin, is given as 4930 feet; and 

 the collections made in the Humbolt Valley, and in Maggie, 

 Susan, Annie and Woodruff Creeks were all taken at about 

 this altitude. The springs in the Cortez Range are at an 

 elevation of about 5,000 feet, and the specimens taken in 

 [ames Creek were all from an altitude of about 6,000 feet. All 

 of the specimens are from streams tributary to the Humbolt 

 River. 



Alv thanks are due to Professor H. B. Ward and to Dean 

 E. A. Birge for the loan of the proof sheets of the former's 

 "Fresh-Water Biology", wdiich were used in the determination 

 of the Cladocera and Ostracoda. 



COPEPODA. 



1. Cyclops viridis americanus Ilerrick. — This species was 

 collected twice during July in ponds along the Humbolt River. 



ci,adoce;ra. 



2. Siniocephahis serrulatus (Koch). — Taken in a pond 

 along the Humbolt River on July 8. 



3. Sir.wcephalus vetuhis Mueller. — This species was ap- 

 parently common in the ponds along the Humbolt River, Susan 

 Creek, and Maggie Creek. It appeared in ten collections made 

 betw-een July 5 and 22. 



4. Chydonis sphaericus (O. F. Muller). — A single speci- 

 men was collected in a pond near the Humbolt River, July 5. 



5- Cypridopsis vidua O. F. Muller. — Occurred in a pond 

 near the Huml^olt River, July 5. 



6. Cypris vircns Jurine ( ?). — A single specimen, probably 

 referable to this species, was collected from Maggie Creek with 

 a number of Simoceplialus vetulus, July 11. 



