ISOPODS OF NORTH AMERICA. 



181 



The first antennas extend to the posterior margin of the first thoracic 

 segment. The first two articles of the peduncle of the second pair of 

 antennae are short and about equal in length; the third is a little longer 

 than the second; the fourth and fifth are subequal and each about 

 twice as long as the third. The flagellum is composed of fifteen 

 articles.. The second pair of antennae extend a little beyond the pos- 

 terior margin of the second thoracic segment. The maxilliped has a 

 palp of five articles. The frontal lamina is very small, somewhat cone- 

 shaped, with base small and irregularly rounded and rather convex. 



Fourth, fifth, and sixth segments of the thorax longer than the other 

 four. The epimera of all the segments, from the second to the seventh, 



inclusive, are distinctly sep- 

 a arated from the segments. 



The posterior angles of the 

 last three segments are pro- 

 duced beyond the posterior 

 margins of the segments, the 

 posterior angle being very 

 acute. In the last three seg- 



162. JEGA 



INCISA (AFTER 



A R G E R ) . 



PIG. 163. ^EGA INCISA (AFTER SCHI- 

 (EDTEANDMEINERT). O, FRONTAL LA- 

 MINA AND BOTH PAIRS OF ANTENNJ5. 

 j, YOUNG FEMALE. C, LEFT LEG OF 

 THIRD PAIR. (ENLARGED.) 



FlG. 164. ^EGA INCISA. a, MAXILLIPED. 



x 39. b, SECOND LEG. x 11|. 



ments a distinct carina extends obliquely from the outer posterior 

 angle to the middle of the side adjacent to the segment. In the 

 epimera of the three anterior segments the carina extends obliquely 

 from the outer post-lateral angle to the inner antero-lateral angle. 



All six segments of the abdomen are distinct. The first is parth^ 

 covered by the last thoracic segment. The lateral parts of the seg- 

 ments are not distinctly separated from the dorsal portion. The sixth 

 or terminal segment is broadly triangulate, with a small round emar- 

 gination at the apex. On either side of this emargination the posterior 

 margin is denticulate and crenulate for a short distance. There are 

 four spines on either side of the medium notch. The uropoda extend 



