ENTOMOSTRACA OF MINNESOTA. 57 



l>iaptoiiius wierzejskii Eichard. 



Plates VIII, Fig. 4; IX, Fig. 13. 



Richard '88; De Guerns aad Richard '89. 



A rather large species which is obviously very near, if not a 

 variety of J), serricovnis. The caudal stylets equal the preceding seg- 

 ment. The antennte do not exceed the second abdominal segment and 

 in the male are armed as described above. The internal rami of the 

 fifth feet of the female are one Jointed. The species has beenencoun 

 tered in Spain and Sixouy. Length 2.75 mm. 



Diaptoiiiiis ^ pectinicoruis Wierzejski. 



Plate X, Fig. 3. 

 Wierzejski '87; De Gaerne and Richard '89. 

 This species can only be separated with difficulty from the other 

 members of this section. Making some allowance for the different 

 positions and distortions assumed under the microscope some diverg- 

 ence is to be expected. The caudal stylets are a little longer than the 

 preceding segment. Antennae reach to the stylets. The dentate plate 

 on the antepenultimate segment of the right mile antenna has abDut 

 fifteen strong teeth on its distal half. 1.8 mm. long. 



* Diaptomus trybonii Lilljeborg. 

 Plates VIII, Fig. 17; IX, Fig. 4; X, Fig. 13. 

 De Gaerne and Richard '89. 

 This is a very peculiar and easily distinguished species. It has 

 but a few minute denticulations at the extremity of the appendage of 

 the antepenult segment of the male antenna, bub, in strictness, must 

 fall into the present section. Rither small (1.5 mm). The last tho- 

 racic segment with a dorsal projection which extends toward the right 

 side. The first abdominal segment in the female also has a large dor- 

 sal process. The caudal stylets are short. The antennae almost reach 

 the base of the stylets. The form of the feet may be gathered from 

 the figures. Oregon. 



Diaptomus hircus Brady. 



Plate XXXLII, Figs. 6-3. 



Brady '91. 



Female. — Seen from above the body is widest in front, thence 



tapering backwards to the hinder end of the thorax, which is a little 



wider than the abdomen. The posterior thoracic angles are mucro- 



nate but not very strongly produced. The anterior antennoe reach 



backwards as far as the posterior end of the thorax. Inner branch of 



