ENTOMOSTRACA OF MINNESOTA. 113 



«ach joint has its series of fine teeth. The free lower margins of the 

 thorax are ornamented with series of prominences, while the last seg- 

 ment is extended into a blunt angle bearing long teeth. The last seg- 

 ment of the abdomen is spiny-margined and is ornamented with a 

 double row of spines at the anus. The armature of the stylets as well 

 as that of the feet is identical with that in typical C. serrulaius. The 

 last two joints of the antenna? measure 0.1 mm. each, while the two 

 previous measure unitedly 0.12 mm. The color is not opaque as in 

 the smaller form usually. Brady's var. montanus has shorter stylets 

 than the type, but seems nearest the small dark form found in peaty 

 waters in America. Cyclops pecUnifer Cragin has no distinctive points, 

 it being typical G. serrulatus. 



Marsh also finds this variety rarely elsewhere than in pelagic locali- 

 ties, and only in occasional association with the type. Schmeil notes 

 discrepancies in the original measurements of the two forms, and is 

 led to doubt their distinctness. It can only be replied that the distinc- 

 tions insisted on do actually exist, and are very apparent when the 

 forms are before one, and are sufficiently obvious from the measure- 

 ments given above. 



Cyclops macrurus Sars. 



Sars '63; Uljanin '74 (alajensis); Brady '78; Rehberg '80; Sostaric '80; Herrick '84; 

 Vosseler '89; Lande '90; Richard '91; Schmeil '91 and '92. 



This form is so close to C. serndatus as to suggest the question 

 whether it is more than a well-marked variety. From that species it 

 differs in the shorter antennje which are hardly longer than the first seg- 

 ment, the slender, smooth abdomen, and the greatly elongated stylets, 

 which lack the lateral line of teeth. The feet and the proportional 

 length of the joints of the antennfe are as in serrulatus. The species 

 occurs in Scandinavia and Germany, but rarely. 



Cyclops prasinus Fischer. 



Jurine '20; Fischer '60; Vernet '71 (longicornis); Vosseler '86 (pentagonus); Richard 

 '87 (pentagonus var. vichyensis) and '91 (pentagonus); Schmeil '91 (pentagonus) 

 and '92. 



Cephalothorax broad, attenutated behind. Abdomen slender, 

 nearly cylindrical. Stylets one and one-half as long as last abdominal 

 segment. Lateral seta a little distad of the middle. Outer apical seta 

 forming a strong spine and about as long as the inner slender seta. 

 Longest seta four times the length of the stylet, shorter median seta 

 three-fourths as long. Antenna reaching the end of third thoracic 

 segment, proportions and armature as in C. serruJatvs. Fifth foot 

 one-jointed, closely resembling that of C. serrulatus, but the external 

 seta is delicate and not a strong, heavy spine. Ova few, appressed. 

 Length 0.8 to 0.9 mm. Color green. 



