458 Wisconsin Academy of Sciences^ Arts, and Letters. 



order of the other descriptions, was received while this paper 

 was going through the press. Consequently the author has not 

 seen the type specimens, and there has been no opportunity to 

 prepare figures. Pearse speaks of it as related to Lintoni, and 

 it is evident that it falls into the leptopus group, being closely 

 related to stagnalis as well as Lintoni. The form f the endo- 

 podite of the left fifth foot of tlie male is a distinctive charac- 

 teristic. 



DIAPTOMUS SIGNICAUDA Lilljcborg. 



Plate XXI, figs. 8, 10, 11. Plato XXII, fig. 3. Plate XXIII, 



fig. 3. 



1889. Diaptovius signicauda DeGuerne and Richard, p. 55 ; 



pi. I, figs. 15, 16, 31 ; pi. Ill, fig. 22. 

 1895. Diapiomus signicaudatus Herrick and Turner, p. 63; 



ph VIII, fig. 13; pi. IX, fig. 10. 

 1897. Diaptomus slgvlcauda Scluicht, p. 104; pi. XXIX, figs. 



3-6. 



A small species. The cephalothorax is broadest in front 

 of the middle at the second seginent. The first segment is 

 about twice the length of the second. The last two segments 

 are confluent, and the last segment has rather broad projecting 

 lateral lobes with acute posterior angles ending in small spines. 

 The fourth thoracic segment has a slight dorsal gibbosity. 



The first abdominal segment of the female is expanded in 

 front and laterally, and is armed laterally with minute spines; 

 on the posterior end on the right side it bears a finger-like proc- 

 ess which projects backward. This process is somewhat vari- 

 able in length. The second abdominal segment varies in length. 

 In some cases it is hardly to be distinguished from the first 

 segment (PI. XXI, fig. 11), while in others it equals in length 

 the third segment (PI. XXIII, fig. 3). The f ureal rami vary 

 in length from one and a half times the breadth to twice the 

 breadth. Thev are setose on the inner raar<2;in. 



