STATE GEOLOGIST. 147 



of equal width; caudal stylets longer than the last two seg- 

 ments of the abdomen terminal; setae of moderate size, inner 

 three times as long as outer, internal pair nearly equal. Antennae 

 as long as first two segments. The inner ramus of fourth foot has 

 the exterior thorn very small. The second joint of the fifth foot is 

 small and the external thorn very small. Length 1.5 mm. 

 Not seen in America. 



B. — First joint of fifth foot of moderate size. 



(a) Terminal segment of fifth foot with one long seta and a 

 short thorn. 



These small species pass into the above group and constitute one 

 of the most difficult groups of the genus. The distinctions offered 

 are very small and specific variation considerable. 



Sp. 6. Cyclops strenuus, Fischer. 



f C. piCtUS, KOCH. 



C brevicaudatus, claus, liUBBOCK, heller, fric. 

 C. strenutis, saks, brady. 



Antennae reaching about to the end of the third segment; caudal 

 stylets slender, three times as long as the last segment; the outer of 

 the caudal setae shortest. The third seta is over once and one half 

 the length of the stylet. 



Sp. 7. Cyclops lucidulus, Koch. 



C. lucidulus SARS . 



C. furcifer, claus. 

 C. vernalis, fischer. 



This species is given on the authority of Rehberg. Claus con- 

 sidered C. furcifer a large variety of the above species. 



The antennae are as long as the first segment; the fifth foot is 

 peculiar in form, with the second joint armed with a spine and a 

 hook; length 1.3 mm. 



Neither this nor the previous species is known in America.* 



Sp. 8, Cyclops robustus, Sars. 



Antennae shorter than first segment, thick. Body depressed, 

 first segment broad and rounded anteriorly, the others spreading; 

 leaudal stylets nearly parallel, long; inner median seta much the 



*C. palchellus, Brady is not C. puichellus, Koch, and may be the above species. 



