I8OPODS OF NORTH AMERICA. 



365 





Body oblong, ovate, almost three times longer than wide, 7 mm. : 20 

 mm.; length of abdomen a little more than one-third that of entire 

 body, 8 mm. : 20 mm. 



Head wider than long, slightly excavate in front. Eyes large, 

 round, compound in structure, and situated just anterior to the median 

 transverse line on the anterior portion of the head, at the extreme 

 lateral margin. First pair of antennae with the basal article not 

 expanded, and equal in length to the second article; third and fourth 

 articles slightly longer than either of the preceding ones. First antennae 

 extend to the end of the third peduncular article of the second pair of 

 antennas. The basal article 

 of the second antenna? is 

 short; the second and third 

 articles are about equal in 

 length; the fourth is very 

 little longer than the third; 

 the fifth is about twice as 

 long as the third. The fla- 

 gellum consists of fourteen 

 articles. When retracted, 

 the second antennae extend 

 to the middle of the third 

 thoracic segment. The 

 maxillipeds have a palp of 

 four articles. 



The segments of the 

 thorax are about equal in 

 length, with the exception 

 of the first, which is some 

 what shorter than any of 

 the others. Theepimeraof 

 all the segments occupy the 

 entire lateral margins of the segments. They are in the form of large, 

 broad plates, gradually increasing in width from the first to the sixth. 



The legs are more or less alike in structure, and have a few hairs on 

 the inferior margins. 



The abdomen has two short segments followed by a long terminal 

 one with sutures at the base. The sides of the abdomen converge to a 

 narrow extremity, the width of which is to the base of the abdomen as 

 2:5. The posterior margin of the terminal segment is produced in the 

 middle in an acute point, extending some distance beyond the lateral 

 angles. Color varies greatly, being sometimes uniformly light or 

 dark green, or brown and often striped with a median longitudinal 

 stripe of a light color and a marginal stripe on either side, or with 

 only marginal stripes. The colors are occasionally arranged in trans- 

 verse bands or blotches. 



FIG. 395. IDOTHEA BALTICA. a MAXILLIPED. X 41. 

 b FlEST ANTENNA. X 23. 



