﻿NORTH AMERICAN NOTOSTRACA — LINDER 35 



males, where it can reach a length of 40—^2 ])ercent of the length of 

 the carapace (in type specimens), thus by far exceeding the length in 

 any other species of Lepidurus I have examined. In the females, 

 however, we find quite an ordinary length of this plate to be 17-29 

 percent of that of the carapace. A reliable character, for both sexes, 

 is that the supra-anal plate has a distinct keel middorsally, furnished 

 with a large number of spines (from 20 up to more than a hundred). 

 Most of these spines are minute, much smaller than in other species, 

 but there are also larger ones interspersed at varying intervals, and 

 intermediate sizes occur, too. However, the largest spines do not 

 quite reach the size usual in other species. Another conspicuous 

 character is the shortness of the telson. Its length, disregarding the 

 supra-anal plate, is less than half of its width. 



Packard (1883, p. 317) says about the spines on the posterior 

 emargination of the carapace that they show a tendency to become 

 obsolete on the lower part of the emargination, and that they are 

 finer than in "the Em-opean species." I confirm this. They have a 

 rather worn appearance, though variations occur. 



So far as I can see, the number of pairs of legs is not given by 

 earlier authors. I have found it to be 35 to 40. 



For other particulars, see table 1 . 



Localities. — The following American localities are represented in 

 the material examined by me: Montana, 2cf and 19 (co types), 

 U.S.N.M. No. 11605; 2d' (cotypes), Stocldiolm Museum. Idaho, 25 

 miles north of Ashton, 2cf and 29 (U.S.N.M. No. 55800); "Idaho," 

 w4thno particulars, 1 specimen, badly preserved (U.S.N.M. No. 50569). 

 Max, N. Dak., 19 (U.S.N.M. No. 67699). Rocky Point Pond, 

 about 15 miles west of Klamath Falls, lOamath County, Oreg., eleva- 

 tion about 4,300 feet ("L. lemmoni," Coopey, 1946, p. 339), 3 speci- 

 mens clearly belonging to this species. Canada, with no particulars, 

 Id, typical (U.S.N.M. No. 49121). Medicine Hat, Alberta, 2d 

 (U.S.N.M. No. 54814). 



Of material from Europe and Asia I have seen specim.ens from the 

 following localities. Northern Siberia, Nikoulina, Icf, Stocldiolm 

 Museum No. 561; Igarskoj, Id, Stocldiolm Museum No. 1433; 

 Worogoba, Id and 19, Stockholm Museum No. 549; Jenissejsk, 29, 

 Uppsala Museum; Mcllraddinka, Kulundinsk Steppe, 2 specimens, 

 (U.S.N.M. No. 82060.) 



The species is further reported in America from Smitlifield, Cache 

 VaUey, Utah (Packard, 1883). From the following places in Canada: 

 near Winnipeg, Manitoba; Dufton, Saskatchewan (Johansen, 1921). 

 Outside America, it is given (as L. macrurus) from Arkhangel (Lill- 

 jeborg, 1877), Government of Wolodga (Decksbach, 1924), Koslow, in 

 Government of Tambow (Decl^bach, 1924), Government of Rjasan 

 (Smu-nov, 1936), Northern Caucasus (Smirnov, 1932), all in the 



