FAIRY SHRIMP — LYNCH 555 



drical proximally, but expanding to a widened distal part which extends 

 about 60 percent of its length, and which is approximately 4 times as 

 wide as thick, slightly concave on its lateral side, with the narrower 

 borders anterior and posterior. Near the apex the article contracts 

 a little, then expands into a tip flattened nearly at right angles to the 

 preceding part. In end view, the tip appears like a heel and toe, 

 the more pointed toe being median. A rasplike area of low-flat- 

 topped, chitinized papillae on the posterolateral side of the tip extends 

 about halfway up the lateral border. Thoracic appendages typical 

 of the genus; branchial lamina entire with serrated margin; the 

 endopodite tapering to a slightly inturned end, with characteristic 

 spines on its median border. Genital segments and copulatory 

 appendages typical of the genus. Cercopods 1.5 (0.85-2.5) mm. 

 long, distinctly articulated with the telson, with long, plumose setae 

 on lateral and median borders. 



Female: Length from front to end of cercopods 23 (18.75-30.0) 

 mm. Ratio of length of head-thorax to that of genital segments, 

 abdomen, and cercopods 1:1.33 (1:1.2-1:1.5). Antennule 1.9 (1.75- 

 2.25) mm. long, about the same length as the antenna. Antenna 

 1.97 (1.4-3.5) mm. long, uniarticulate, the distal fifth narrowing to 

 a tapering point. The 1 1 thoracic segments each bear a pair of 

 dorsal verrucose bosses of conspicuous size, which may or may not 

 bear sensor} 7 bristles; those of segments 4 and 9 nearer the middorsal 

 line than the others. Thoracic appendages typical of the genus, 

 the endopodite more obtuse than that of the male, with food-trapping 

 spines of simpler spinulescence. Ovisac narrow anteriorly, expanding 

 at the level of the second abdominal segment to from 2){ to 4 times its 

 anterior width to form right and left conical outpocketings, then 

 contracting to about 65 percent of its maximum width to continue 

 to a bluntly conical posterior end located under abdominal segment 

 4 or 5. Eggs of preserved specimens 295-345 microns in diameter. 

 Cement glands composed of right and left, closely apposed, masses 

 of large cells at the anterior end of the ovisac and on the dorsolateral 

 sides of the posterior half of the uterus. Cercopods 1.36 (1.0-1.75) 

 mm. long, with long, plumose setae on median and lateral borders. 



The smallest mature female encountered was 12 mm. long, with 

 2 eggs in the ovisac, which extended only as far as the middle of the 

 third abdominal segment. 



Type data: One female holotype, USNM 104128, and 12 male 

 and 12 female paratypes, USNM 104129, have been deposited in 

 the U.S. National Museum. The type locality is an alkaline pond 12 

 miles south of the town of Moses Lake, Grant County, Washington. 



Differentiating characters: The males are morphologically 

 very close to B. mackini Dexter (1956). The most obvious differences 



