564 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iis 



ably not over 3 meters) . — The single collection from this lake, August 

 21, 1960, contained 7 adults: 6 9 (5 with ovisacs), 1 cT. 



Ponds and pools near lake 9. — (1) Pool (about 1 mile north- 

 west; estimated area, 25 square meters; maximum depth about 1 

 meter; vegetation largely Carex and Sphagnum), August 23, 1960: 

 1 C VI 9, 1 C VI cf. (2) Pond (about 1 mile southwest; estimated 

 area, 627 square meters; maximum depth about 1.5 meters; vegetation 

 largely Hipperus, Arctophila, Sphagnum) , August 21, 1960: 1 C V9. 



Coastal region south of cape Thompson. — One or two specimens 

 were collected from each of four more or less brackish pools near 

 Singoalik Lagoon in 1960 (table 1). Large numbers of E. gracili- 

 cauda of similar size and habitus (see p. 567), occurred in two of these 

 samples and early copepodid stages (C II-C III) that were present 

 might be either of the two species. In 1961, recognizable stages of 

 E. arctica were not collected in any coastal pools that were sampled. 



Occurrence in Noatak River Watershed 



Locality about 58 miles inland from Chukchi Sea, near junction of 

 Kelly and Noatak Rivers, about 67°58' N., 162°20' W. Tash collec- 

 tion: 12 C V 9^; permanent freshwater pond, area about 0.2 hectares, 

 depth about 1.8 meters, from weedy margin {Carex dominant), July 

 29, 1961; occurring with Diap>tomus gracilis. This region is a part 

 of the Brooks Range physiographic province southeast of Cape 

 Thompson; the Noatak River and its tributaries drain a considerable 

 part of the western portion of the northern mountains of Alaska. 

 Eurytemora yukonensis, not yet known from the Arctic Slope province, 

 also occurred in shallow bodies of water of the Noatak region with 

 D. gracilis. 



Occurrence at Umiat 



Locality on Colville River in northern Alaska, in foothills of Brooks 

 Range, about 65 miles inland from Beaufort Sea, about 69°24' N., 

 152°15' W. Wilson collection: 41 specimens (9 C TV 9^; 32 C V9c?) 

 taken by casting small net an unknown distance from shore in shallow, 

 freshwater permanent pond, estimated area about 0.2 hectares, 

 July 29, 1949, collector, C. S. WUson; occurring with a few specimens 

 of Heterocope septentrionalis (C VI) and Diaptomus prihilojensis (C 

 IV-VI). 



Bionomics 



Restriction to either brackish or fresh water cannot be assumed for 

 species of Eurytemora, but some occur much more commonly in one 

 than in the other. E. arctica was rare in brackish coastal pools and 

 was not found in the lagoons at Cape Thompson, although all other 



