I80PODS OF NORTH AMERICA. 61 



short, being only as long as the first abdominal segment, and narrower, 

 about one-third as wide as the sixth thoracic segment; it could easily 

 be taken for one of the abdominal segments. 



The first five segments of the abdomen are short, distinct, and sub- 

 equal in length; they are but little wider than the seventh thoracic 

 segment, but abruptly narrower than the sixth thoracic segment. 

 The sixth or terminal segment is triangular in shape, with apex very 

 acute. The uropoda extend to the extremity of the abdomen. The 

 inner branch is a little wider and a very little longer than the outer 

 branch. Both are narrow, elongate, with extremities obliquely trun- 

 cate, the post-lateral angles being rounded. 



There are apparently only five pairs of thoracic legs. The first 

 pair are modified and opercular, and are composed of only two arti- 

 cles. The seventh pair are wanting. The remaining five pairs are 

 ambulatory. 



Description of female. Body ovate, about twice as long as wide, 

 2 mm. :4 mm. Head smaller than in male, with the front produced in 

 a lobe which is emarginate in the middle. Eyes 

 small, round, composite, and situated at the 

 post-lateral angles of the head. Antennae of 

 both pairs as in male. 



The first segment of the thorax is short and 

 narrow and almost inconspicuous, appearing as 

 a small lobe back of the head. The thorax 

 becomes wider with the second thoracic seg- 

 ment. The second and third segments are short 

 and about equal in length. The fourth and 

 fifth are very long, many times longer than the FlG- 45- ~ GNATHIA 



' . (AFTER HARDER). FEMALE. 



preceding segments and scarcely to be distin- 

 guished, being somewhat fused dorsally. They are nearly subequal. 

 The sixth segment is about half as long as the preceding segment, and 

 becomes gradually narrower from the anterior to the posterior extrem- 

 ity. This segment is also somewhat fused dorsally with the preceding 

 segment. The seventh segment is very short and narrow and not to 

 be distinguished from the abdominal segments, being of the same length 

 as the five anterior abdominal segments, but narrower. 



The abdomen is similar to that in the male. The five posterior 

 pairs of walking legs are similar to those in the male. The first pair of 

 legs are composed of three articles and terminate in a minute rounded 

 lobe. There is a delicate membraneous plate attached to the base of 

 the first pair of legs. 



The eggs are very clearly seen in the cavity of the thorax, which 

 they almost completely fill. 



Body of female smooth throughout its entire length! 



