FAIRY SHRIMP — LYNCH 559 



of the ovisac. The cement glands vary from light yellow to dark 

 brown but in most adult females are some shade of brown. The eggs 

 within the uterus are usually an ochraceous yellow. The ovary, 

 which extends from abdominal segment 4 or 3 to thoracic segment 

 8 to 4, often contains large oocytes of white, greenish white, or pule 

 blue-green tint. 



The abdomen is colorless except for the intestine, which appears 

 blackish regardless of food content since the dark blue cells mentioned 

 above accompany the intestine along its dorsal side from some part 

 of the thorax to the fourth or fifth abdominal segment and in some 

 individuals completely encircle the abdominal intestine. The cerco- 

 pods are colorless. 



The females are unique among North American species of Branchi- 

 necta in the yellow or orange spots on the outpocketings of the ovisac, 

 and in the similarly colored thoracic bosses. 



Distribution and habitat. B. campestris has been collected in 

 the State of Washington from the following localities : Three ephemeral 

 ponds in the Lower Grand Coulee, Grant County, Washington, and 

 five ponds scattered over an area of rough "scab land," 10 to 17 miles 

 south of the town of Moses Lake, in southern Grant County and 

 western Adams County. Most, or more likely all, of these ponds in 

 Grant and Adams Counties have been destroyed in recent years by the 

 construction of gigantic reservoirs filled with water from the Columbia 

 River. These reservoirs have covered and annihilated some of the 

 largest and most interesting "dry lakes" in North America. In 

 addition, most of the ponds for miles below the dams have been con- 

 verted, by continuous seepage, from ephemeral alkaline ponds into 

 permanent fresh-water ponds in which none of the original unique 

 and scarcely explored fauna of alkali-tolerant organisms has survived. 



One collection came from a pond in Okanogan County, Washington, 

 about 10 miles north of LaFleur. Dr. G. C. Anderson (1958) report ed 

 an unknown Branchinecta from Hot Lake, Okanogan County. Speci- 

 mens that he kindly donated to the writer proved to be B. campestris. 

 Two separate collections came from a pond situated at the eastern 

 border of the town of Rawlins, Carbon County, Wyoming. The 

 specimens from Rawlins differ slightly from those from Washington 

 in that the females have somewhat smaller thoracic bosses, and the 

 males have somewhat larger expansions at the tip of the antenna. 



B. campestris has always been found in water of extremely alkaline 

 reaction, or at least with a high content of dissolved salts. The pH 

 of water carried back to Seattle and determined a day or two later 

 by a Beekman pH Meter, Model G, has ranged from 9.5 to 10. On 

 the two occasions when the density of the water was ascertained, it was 

 1.020 and 1.012 at 60° F. Usually, the new species has been found 



