344 PROCEEDINGS OF TEE NATIONAL MUSEUM. vol. 39. 



second exopod, I-O; 0-1; 1-6: endopod, 0-1; 0-2; 1-4: third exopod, 

 I-O; 0-1; 1-6: endopod, 0-1; 0-2; 1-4: fourth exopod, I-O; 1-5: 

 endopod, 0-1 ; 0-1 ; 1-3. 



Color transparent, except the digestive canal, which is bright blue 

 for its entire length, making the copepod very conspicuous when alive. 

 This color, however, fades and is not visible in preserved specimens. 



Total length, 0.86 to 1 mm. Length of carapace, 0.48 mm. Width 

 of same, 0.4 mm. Length of setae on anal laminae, 0.4 mm. 



Male. — Similar to the female in general body structure, but more 

 slender. First and second antennae shorter and weaker; maxillipeds 

 present as large, three-jointed, prehensile organs; basal joint short 

 and stout; second joint much longer and tapered toward the distal 

 end, armed with two powerful muscles and with a fringe of stiff 

 hairs along its posterior margin; third joint in the form of a long 

 slender claw, twice the length of the second joint and curved into a 

 half circle, its concave margin facing its fellow on the opposite side 

 of the mid-line; the tip is slightly enlarged and bluntly rounded 

 (fig. 28). Genital segment wedge-shaped, widest posteriorly where 

 it carries a long and stout spine on either side; abdomen and anal 

 laminae as in the female. 



Total length, 0.75 to 0.8 mm. Other measurements corresponding; 

 color as in the female. 



{chautauquaensis, from Chautauqua, the place where the first 

 specimens were found.) 



Several specimens of this beautifully colored species were obtained 

 among free swimming forms at the surface of Lake Champlain during 

 the session of the American Society of Microscopists held at Chautau- 

 qua, New York, in 1886. 



They were given to Charles S. Fellows, who published a description 

 of them in the proceedings of the above society for 1887. They had 

 never been found by other observers up to the present year. But in 

 some samples of the tow from Lake Mendota at Madison, Wis. sent 

 to the author by Profs. E. A. Birge and Chauncey Juday of the 

 University of Wisconsin, both sexes of this interesting species were 

 again discovered. These specimens have been placed in the National 

 Museum collection and have been numbered 38617. 



All of this species have thus been found while swimming actively 

 at the surface and the natural host has not yet been discovered. 

 But it is reasonably certain that they are parasites like all the other 

 species of the genus, and that their host will be discovered in due 

 time. 



