PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



SMITHSONIAN INSTITUTION 



U. S. NATIONAL MUSEUM 



Vol. 84 Washington : 1937 No. 3025 



A GIANT NEW SPECIES OF FAIRY SHRIMP OF THE 

 GENUS BRANCHINECTA FROM THE STATE OF WASH- 

 INGTON 



By James E. Lynch 



University of Washington, Seattle, Wash. 



In the spring of 1935, I was given two specimens of an excep- 

 tionally large and apparently undescribed species of Branchinecta by 

 Dr. M. H. Hatch, of the Department of Zoology of the University 

 of Washington. The honor of discovering this giant phyllopod 

 belongs to J. F. Clark, then of Washington State College, who had 

 collected the specimens in the vicinity of Coulee City, Wash., and 

 from whom Dr. Hatch had received them. On May 3, 1936, 1 visited 

 many of the temporary ponds between Coulee City and the Grand 

 Coulee Dam, in one of which I found the giant Branchinecta. 

 Eighty-nine specimens were obtained, of which 39 were males and 50 

 were females. 



The measurements given herein were obtained from 10 mature 

 specimens of each sex, selected to show the range in size of adults. 

 The figures given are averages, with the range following in 

 parentheses. 



Genus BRANCHINECTA Verrill 



BRANCHINECTA GIGAS, new species 



Pistes 77-80 



/Specific diagnosis. — Male : Total length from front to end of cerco- 

 pods 63 (61-70) mm. Length of combined head and thorax some- 

 what less than that of combined genital segments and abdomen. 

 Antennule 5.6 (4.2-7.0) mm in length, terminated by a group of 

 about 30 small sensory hairs. Antenna 12.6 (11-15) mm in length, 



13430—37 555 



