no. 3602 CRAYFISHES — HOBBS, HOLT, AND WALTON 39 



area. It was with C. philadelphica at stations 3, 5, 8, 9, 10, 12, 14, 

 16, 19-22, 24-26, 28, 29, 32-35, 37, 44-46, 48, 50-52, 54-56, 59, 60, 66, 

 69, 71, 74, 76, 77, 94, 98, 106-110, 113, 119, 122-125; with C. heterog- 

 natha at 3-5, 24, 28, 34, 45, 48, 61, 63-67, 72, 79-81, 86, 97, 105, 106, 

 116, 122, 123, 125, 126; with C. jallax at 3, 5, 15, 18, 24, 43, 54-58, 

 61, 63, 65-67, 71, 72, 75, 79, 81, 86, 95-97, 126; with P. alcicomus at 

 3-5, 15, 18, 19, 24, 25, 43, 58, 61, 63-67, 72, 76, 79, 81, 86, 95, 97, 

 104, 105; with C. branchiophila at 15, 18, 20, 24, 29, 43, 55, 57, 58, 

 63, 65-67, 72, 73, 75, 79, 81, 86, 97, 104, 116, 126; with Xg. instabilius 

 at 3-5, 7, 9, 11, 12, 21, 22, 24, 37, 44, 46, 54, 60, 61, 64, 86, 95, 97, 

 123; with B. illuminatus at 5, 16, 19, 20, 22, 34, 44, 45, 48, 51, 59 

 76, 86, 97, 122, 125; with C. ingens at 5, 15, 18, 54, 58, 61, 64, 67, 

 72, 73, 75, 79-81, 86, 95, 97, 104, 116; with A. koronaeus at 14, 18, 

 19, 29, 52, 69, 71, 72, 77, 98, 110, 125; with C. holostoma at 7, 10, 11, 

 18-23, 25, 37; with Xd. jormosus at 10, 21; and with A. legaeus at 81. 

 Remarks. — Not only is Dn. Ueata the most variable ostracod in 

 the region, it is perhaps the most aggressive. In all instances in 

 which it was found associated with other ostracods, it was the most 

 abundant, and it occurred unaccompanied by other ostracods in a 

 far greater number of instances than any of the other species. 



Donnaldsoncy there scalis Hobbs and Walton 



Figures 7d, 9<z 

 Donnaldsoncythere scalis Hobbs and Walton, 1963, pp. 364-366, figs. 1-5, 25. 



Diagnosis. — Copulatory complex with peniferum terminating 

 ventrally in scooplike expansion; clasping apparatus forming gentle 

 arc, not divisible into vertical and horizontal rami, internal border 

 with two teeth and apical border with four serrations. 



Range. — Apparently restricted in the Mountain Lake region to 

 Little Stony Creek (New River drainage) and two tributaries to 

 Johns Creek and Potts Creek (James River drainage) in Giles County, 

 Va., and Monroe County, W. Va.; elsewhere in the Susquehanna 

 River drainage system in Luzerne and Wyoming Counties, Pa., and 

 in a tributary of Lake Cayuga, Cayuga County, N.Y. 



Specimens examined. — Approximately 325 specimens from 16 

 collections in the following stations: 1, 2, 7, 17, 38, 39, 44, 68, 82, 83, 

 100, 101, 103, 114, and 115, at elevations of 671 to 1219 m. 



Hosts and associates. — Donnaldsoncythere scalis was associated 

 with Cambarus b. bartonii at all stations, with C. sciotensis at 44, and 

 with 0. juvenilis at 7. 



Except at stations 7, 38, 44, 82, 101, and 103, it had no ostracod 

 associates; at these it was accompanied by P. phyma; Dn. Ueata and 

 E. kanawhaensis were also present at 44. 



