82 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



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

 being submembranaceous; the peduncle of the second pair of pleopods is 



somewhat wider than long Genus Cirolana Leach 



ef. First and second pairs of pleopods not similar to each other; first pair of 

 pleopods with both 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 Conilera Leach 



d'. 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 Cirolanides Benedict 



cf . Peduncle of the second pair of antennae 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 antennae. 



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

 underside of abdomen and not branchial in function. 



Genus Eurydice Leach 



d'. Maxillipeds composed of two articles. Uropoda attached to the under- 

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



pleopods Genus Branchuropus Moore 



b' '. Supplementary ramified branchiae developed at the base of the inner branches 

 of the pleopoda. Eyes placed entirely on inferior side of head. 



Genus Bathi/nomus A. Milne Edwards 



a' '. Five anterior segments of abdomen fused to form a single segment anterior to 

 large terminal segment Genus Colopisthus Kichardson 



19. Genus CIROLANA Leach. 



First pair of antennae with basal article of peduncle not extended 

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

 second pair of antennae composed of five articles." 



The plate of the second article of the maxillipeds furnished with 

 hooks. 



Abdomen with all six segments distinct. 



The first 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. 



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

 segment. 



c. Body short. Sides of head angulated. First pair of antennae 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. 



Cirolana sphseromiformis Hansen 



a Hansen recently states that in three species of Cirolana the peduncle of the second 

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



