151 TWELFTH ANNUAL REPORT. 



miual three-spined division; caudal stylets twice as long as last ab- 

 dominal segment; seta all nearly terminal, inner one long. Length 

 2.5 mm. 



Common in America, England, continental Europe, etc. C. clau- 

 sii, Poggenpol, is kjiowu to me only from the citations of Rehberg 

 and the translation given by Cragin, hence I can not judge authori- 

 tativ^ely of its validity. Certain points in the translation are obvi- 

 ously erroneous, as where the larger branch of the fifth foot is spoken 

 of. No distinctions sufficiently clear to enable us to separate it 

 from C. tenuicornis can be gathered. 



III. — Fifth Foot 3-jointed. 

 (See Cyclops modestus.) 



Aiitenure IG- jointed. 



There are a few forms which, although they might more properly 

 be ranked with the previous section, seem rarely or never to acquire- 

 more than sixteen joints. 



Sp. 18. CycloiTp languidus, Sais. 



Thorax attenuated posteriorly, caudal stylets exceeding in length 

 the two preceding segments, internal seta short, half as long as the 

 outer, the inner of the median setae as long as the abdomen. Both 

 rami of the first foot and the inner of the second are two-jointed.. 

 Second joint of the fifth feet sub-linear, armed with a seta and a 

 spine. The fact that some of the feet have two-jointed rami sug- 

 gests a young stage of some other forms. 



This species has not been seen in America. 



Sp. 19. Cyclops modestus, Henick. 



(Plate R. Figs. 1—5.) 



American Naturalist, 1883, p. 500 (May). 



This small species, 1.0 mm. long, was first recognized in Cullman- 

 county, Alabama, but occurs also in our lakes. The color varies, but 

 very characteristic is the peculiar shining or glaucous surface of the 

 strongly arched thoracic shield and the evenly curved segments of 

 the abdomen. The antennae reach but little beyond the very long 

 first segment; they are usually 16-jointed, but I have notes of a 

 similar form in which the antennaj are 17-jointed, The feet are- 



