ENTOMOSTRACA OF MINNESOTA. 10 L 



Cyclops lacustris Sars. 



Cephalothorax sub-ovate, truncate in front. Abdomen of equal 

 width throughout; caudal stylets longer than the last two segraents of 

 the abdomen; terminal setiie of moderate size, inner three times as 

 long as the outer, internal pair nearly equal. Antennae as long as the 

 first two joints of the body. The inner ramus of the fourth foot has 

 the exterior spine very small. Second joint of fifth foot small and 

 external spine minute. Length 1.5 mm. It is suggested by Sehmeil 

 that this species, with C. scutifer and C. abyssorum, should be regarded 

 as synonyms for C. strennus. Upon this matter I can offer no opinion, 

 nor does the brief description repeated above help the matter much. 



* Cyclops pulchellus Koch. 



Koch '41; Sars ' 57; Claus '57 and '63 (bicuspidatus) ; Heller '70 (bicuspidatus) ; Fric 

 '72 (bicsupidatus); Hoek '78 (bicuspidatus); Rehberg '80\ and 80^, (helgolandicus); 

 Vejdovsky '82; Herrick'83 (pectinatus); Forbes '82 (thomasi); Daday'tiS (entzii, and 

 pulchellus); Vosseler '86; Sostaric '88; Thallwitz '90; Lande '90; Sehmeil '91 and 

 '92 (bicuspidatus); Richard '91 (bicuspidatus); Brady '91 (bicuspidatus, and 

 thomasi); Forbes '91 and '93 (thomasi); Marsh '93. 



Sehmeil and Marsh agree in regarding G. thomasi of America as 

 identical with G. cuspidatus, and in this we are inclined to concur in 

 spite of certain differences in variable characters. 



Instead of the original description of Forbes, we reproduce that 

 given in the Report on the Invertebrate Fauna of the Yellowstone Parh^ 

 It is to be noticed that Forbes regarded, in his earlier report, certain 

 spines as apical (in his description of the feet) which may be more 

 logically described as lateral. 



A long and slender species, with 17 jointed antennte, oval cephalo- 

 thorax, somewhat closely articulated, slender abdomen, very long and 

 slender caudal rami, and two developed setie to each ramus, the 

 longer of which is about twice as long as the shorter. 



The cephalothorax is widest near the middle, its greatest width a 

 little more than half its length. Posterior angles not prominent or 

 produced, except those of the last segment, which are slightly pro- 

 duced outwards. Sides of the first segment subparallel, rounding 

 slightly toward the front, the segment itself twice as long as the other 

 segments combined; the second segment shorter than the third, but 

 longer than the fourth; the fifth reduced to a narrow linear band, as 

 seen from above, the extremities of which project a little beyond the 

 lateral outline. Abdomen with furca, a little shorter than the 

 cephalothorax, its greatest width one-fourth of its length, including 

 furca. First segment in the female as long as all the others together, 

 broadest in front, its lateral outlines emarginate behind the anterior 

 angles. Posterior margin of last segment serrate beneath and at sides; 



