18 PROCEEDINGS OF THE NATIONAL MUSEUM voe.. 82 



3. Fifth abdominal segment in male with two projecting processes; 



terminal segment of female fifth foot armed with six spines. 



nevadensis Lilljeborg 

 Fifth abdominal segment in male with one projecting process; 

 terminal segment of female fifth foot armed with five spines. 



nordenskioldi Lilljeborg 



4. Last thoracic segment of female expanded in large rounded 



lobes ; terminal segment of female fifth foot ending in a short 

 conical point and having three spines in its external border. 



baikalensis Sars 

 Last thoracic segment of female with shorter wings than in 

 baikalensis ; terminal segment of female fifth foot armed with 

 three terminal spines chankensis Rylov 



EPISCHURA LACUSTRIS Forbes 



Plate 9 ; Plate 10, Figukbs 3-5 ; Plate 11, Figure 1 



(?) Scopiphora vagans PiCKsajiNG, in DeKay, 1844, p. 62. 



Epischura lacustris Foebes, 1882, pp. 541, 648, pi. 8, figs. 15, 16, 21, 23, pi. 9, 

 fig. 8 ; 1891, p. 704, pi. 1, figs. 1-5, pi. 2, fig. 7.— Hebrick, 1884, p. 131, pi. 

 Q, fig. 13.— DE GuERNE and Richard, 1889, p. 90. pi. 4, figs. 3, 9, 10.— 

 Maesh, 1893, p. 200, pi. 4, fig. 6 ; 1895, p. 10, pi. 2, figs. 1-6, pi. 3, figs. 1-6 ; 

 1918, p. 756, fig. 1175.— Herbick and Turner, 1895, p. 82, pi. 13, fig. 15.— 

 ScHAOHT, 1898, p. 260.— ToLLiNGEK, 1911, p. 154, fig. 0'.— Wilson, 1929, p. 

 126. 



The abdomen of the female (pi. 10, tig. 5) is bent to the right. The 

 first segment is short, the second about equal in length to the rest 

 of the abdomen and the furca. The second segment is produced at 

 the right in a rounded process. The spermatophore is ordinarily 

 curved but not wound about the abdomen, as in E. nordenskioldi. 

 The furcal rami are broad. The spines at the external distal angles 

 are stout, the right one being much broader than the left. Of the 

 terminal setae, the outside ones are much broader than the others. 



The 5-segmented abdomen of the male (pi. 10, fig. 3) is strongly 

 bent to the right with processes projecting to the right from the 

 second, third, and fifth segments. The process of the second seg- 

 ment is triangular, about as long as the segment is wide, with a 

 rounded recurved tip ; the distal border is sinuate and indistinctly 

 toothed. The process of the third segment is similar in form and 

 size to that of the second; it is armed at the tip with a rugose pad 

 on both proximal and distal margins. From the right dorsal sur- 

 face of the fifth segment there extends forward a smooth, spatulate 

 process; from the ventral surface there extends to the right another 

 similar process, which terminates in five to seven rather large teeth ; 

 its distal margin back from the tip is finely denticulate, the denticu- 

 lations extending back to the furca; the spines of the furcal rami 

 are not so prominent as in the female, and the furcal setae are of 

 about equal width. 



