56 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



VI. Male with the antepeaultimate joint of the right antenna not armed 

 with hook or plate. 



a. Internal ramus of the right male fifth foot longer than the basal 



joint of the outer ramus. 



* Internal branch of right fifth foot of the male one-jointed, oregoueiisis, 72; 



pallidas, 73; pisciupe, 74; laciniatus, 74. 



** Internal branch of the right fifth foot of the male two-jointed. . castor, 74; 



glacialis, 75; mirus, 75; sancti-patricii, 75. 



b. Internal ramus of the right fifth foot of the male shorter than the 



basal joint of the outer ramus. 



* This internal ramus greatly expanded lilljeborgi, 76. 



** Inner ramus of the right fifth foot of the male not enlarged. 



t Abdomen asymmetrical. . . roubaiii, 76; tyrelli, 76; tbeeli, 77; 

 lobatu.s, 77; affiuis, 77; ainblyodou, 78; niississippiensis, 78. 

 (D. birgei, 79.) 



Diaptonius asiaticus Uljanin. 

 Plate X, Fig. 7. 

 Uljanin '75 ; De Guerne and Richard '89. 

 This seems to be a curious depauperate form found by Uljanin in 

 the desert of Kisil-Kum, Siberia. The peculiar form of the fifth feet 

 of the male together with the hook at the extremity of the right male 

 antenna serve to distinguish it. Length of female, 1.76 mm.; of an- 

 tennae, 1.31 mm. Color, red. 



Diaptonms denticornis Wierzejski. 

 Plate X, Fig. 4. 

 Sars '63 (castor); Wierzejski '83 and '83 (gracilis), and '87. 

 This is one of the large species (3.0 mm. long). It was identified 

 by Sars with D. castor. Although originally found in Scandinavia, 

 it appears to occur in suitable stations throughout Europe. The an- 

 teunoe are short, scarcely exceeding the third abdominal segment. 

 The last segment of the right antenna of the male hooked, the penul- 

 timate segment with a hyaline plate. The figures illustrate the char- 

 acters of the fifth feet. 



Diaptonms serricornis Lilljeborg. 



Plates VIII, Fig. 14; IX, Fig. 12. 



Lilljeborg '88; De Guerne and Richard '89. 



A species of moderate size 1.80 mm. long, characterized by the fact 



that the antepenultimate of the right male antenna bears a projecting 



plate furnished distally with coarse teeth. The fifth feet of the male 



are also characteristic. The last thoracic segment bears small spines 



laterally. The caudal stylets about equal in length the two preceding 



segments combined. The antennne in the female nearly reach the end 



of the stylets and are said to be 23-jointed. The species was found 



in lakes of the Eassian tundras. 



