82 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



e. First and second pair of pleopods similar to each other, the inner branch 

 being sul>membranaceous; the iseduncle of the second pair of pleopods is 



somewhat wider than long .Genus CiroJana Leach 



e\ First and second pairs of pleopods not similar to each other; first pair of 

 pleopods with l)oth branches hard, and forming a large operculum. 

 Second pleopods of the usual structure; the peduncle of the second 



pleopods is scarcely wider than long Genus ConUera Leach 



cV. Only first pair of legs prehensile. The six following pairs are ambulatory. 

 Uropoda with the inner angle of the peduncle not produced. Eyes 



wanting Genus Cirolanldes Benedict 



c'. Peduncle of the second pair of antennas composed of four articles. Plate of 



the second article of the maxillipeds not furnished with hooks. First pair 



of antennae with basal article of peduncle extended straight in front at a 



right angle to the remaining part of the antennas. 



d. Maxillijieds normal, composed of seven articles. Uropods not attached to 



underside of abdomen and not branchial in function. 



Genus Earydice Leach 

 d'. Maxillipeds composed of two articles. L^ropoda attached to the under- 

 side of abdomen, and branchial in function, being similar to the 



pleopods Genus Branchuropus Moore 



y. Supplementary ramified branchite developed at the base of the inner branches 

 of the i^Ieopoda. Eyes jilaced entirely on inferior side of head. 



Genus Buthiiiiomna A. ISIilne Edwards 



a\ Five anterior segments of abdomen fused to form a single segment anterior to 



large terminal segment Genus OdopiMluts Richardson 



19. Genus CIROLANA Leach. 



First pair of anteniift^ with basal article of peduncle not extended 

 straight in front at right angles to second aiticle. Peduncle of the 

 second pair of antennae composed of live articles." 



The plate of the second article of the maxillipeds furnished with 

 hooks. 



Abdomen with all six segments distinct. 



The lirst and second pairs of pleopods similar to each other, the inner 

 branch being submembranaceous; the peduncle of the second pair of 

 pleopods is somewhat wider than long. 



The peduncle of the uropoda has the inner angle strongly produced. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS CIROLANA. 



a. Eyes present. 



h. Fifth abdominal segment with lateral angles free, not covered by the fourth 

 segment. 



c. Body short. Sides of head angulated. First pair of antenn;e short, reaching 

 only to the posterior margin of the head. Frontal lamina forming a large 

 rounded projection, extending beyond the apex of the head and separate 

 from the frontal process. Inner branch of uropoda much longer than outer 

 branch. Terminal abdominal segment tricarinated. 



Clrolana spJueromiformis Hansen 



"Hansen recently states that in three species of Ctrotona the peduncle of the second 

 pair of antenna' is composed of six articles, C. borealis being one of these. 



