I8OPODS OF NORTH AMERICA. 83 



c'. -Body oblong, ovate. Sides of head rounded. First pair of antennae long, 

 reaching to or beyond the posterior margin of the first thoracic segment. 

 Head produced in front in a process continuous with frontal lamina. Inner 

 branch of uropoda not longer than outer branch. Terminal abdominal 

 segment not tricarinated. 



d. First pair of antennae extend to the posterior margin of the first thoracic 

 segment. Second pair of antennae extend to the posterior margin of the 

 third thoracic segment, and are provided with a brush-like structure on 

 flagellum. Inner branch of uropoda shorter than outer branch. Termi- 

 nal abdominal segment smooth Cirolana mayana Ives 



d' '. First pair of antennae extend to the posterior margin of the third thoracic 

 segment. Second pair of antennae extend to the posterior margin of the 

 fifth thoracic segment, and are not provided with brush-like structure on 

 flagellum. Branches of uropoda of equal length. Terminal abdominal 

 segment with basal portion raised above posterior portion, with well- 

 defined edge separating the two parts. 



e. First pair of antennae with joints of peduncle subequal. Terminal abdom- 

 inal segment posteriorly rounded. Basal portion of terminal abdom- 

 inal segment with median lobe produced in two points, one on either 



side of the median line Cirolana linguifrons Richardson 



e? . First pair of antennae with first article longer than second, and third 

 article twice as long as second. Terminal abdominal segment poste- 

 riorly triangular, with apex acute. Basal portion of terminal abdom- 

 inal segment with median lobe truncate. . . Cirolana chittoni, new species 

 b. Fifth abdominal segment with lateral parts covered by the fourth segment. 

 c. Frontal lamina posteriorly or clypeus anteriorly produced horn-like, espe- 

 cially so when seen from the side Cirolana minuta Hansen 



c'. Frontal lamina and clypeus unarmed, not produced horn-like; anterior mar- 

 gin of the clypeus manifestly united with the frontal lamina. 

 d. Frontal lamina narrow, elongate, from four to six times longer than broad. 

 e. Extremity of exterior margin of inner branch of the uropoda erparginate. 

 /. Terminal segment of abdomen emarginate at its extremity. 



Cirolana concharum (Stimpson) 



/'. Terminal segment of abdomen not emarginate at its extremity, pos- 

 terior margin entire. 



g. Second pair of antennae, with flagellum composed of twenty articles, 

 extend to the posterior margin of the second thoracic segment. 

 Terminal segment of abdomen furnished with spines. Outer branch 

 of uropoda extends about six-sevenths of the length of the inner 

 branch. Inner branch of uropoda, below emargination, is wide, 

 posteriorly truncate or slightly emarginate. Epimera with im- 

 pressed lines Cirolana impressa Harger 



g / . Second pair of antennae, with flagellum composed of ten articles, 

 extend to the middle of the first thoracic segment. Terminal 

 segment of abdomen not furnished with spines. Outer branch of 

 uropoda extends about three-fourths of the length of the inner 

 branch. Inner branch of uropoda below emargination is narrow 

 and posteriorly pointed. Epimera without impressed lines. 



Cirolana polita (Stimpson) 

 e' '. Extremity of exterior margin of the inner branch of the uropoda not 



emarginate. 



/. Eyes small, black, longer than wide. Branches of uropoda narrow, lan- 

 ceolate, somewhat elongated; inner branch almost three times longer 

 than wide. Clypeus even. Terminal segment posteriorly rounded. 



Cirolana borealis Lilljeborg 



