ISOPODS OF NORTH AMERICA. 



361 



Body narrow, linear, filiform, about four times longer than wide, 

 4: mm.: 17 mm.; length of abdomen about one-third that of entire 

 length of body, 6 mm, : 17 mm. 



Head wider than long, with anterior margin slightl}" excavate. 

 Anterior portion of head but slightly wider than posterior portion. 



FlG. 389. IDOTHEA RECTILINEA. 



FIG. 390. IDOTHEA RECTILINEA. a, MAXILLIPED. 

 b, FIRST ANTENNA, x 23. 



x 23. 



E} r es very small, transversely ovate, compound in structure, and situ- 

 ated about the middle of the extreme lateral margin. First pair of 

 antennae with the basal article enlarged; second and third articles 

 equal in length, and somewhat shorter than the basal joint; fourth 

 article clavate and a little longer than either of the two preceding 

 ones. The first antennae extend to the middle of the third peduncular 

 article of the second pair of antennae. The basal article 

 of the second antenna is scarcely visible from a dorsal 

 view; the second and third articles are of equal length: 

 the fourth and fifth are subequal and each is about twice 

 as long as the third. The flagellum is composed of 

 thirteen long, slender articles. When retracted, the 

 second antenna? extend to the posterior margin of the 

 fourth thoracic segment. The maxilliped has a palp of 

 four articles. 



The segments of the thorax are about equal in length, 

 the first one only being a little shorter than the others. 

 The first segment is not wider than the head. The epimera of the 

 second, third, and fourth segments occupy the anterior half of the seg- 

 ments, and are very narrow; the epimeron of the fifth segment occupies 

 the anterior two-thirds part of the segment; the epimera of the last 

 two segments occupy the entire lateral margin. 



FIG. 391. IDOTHEA 

 RECTILINEA. AB- 

 DOMEN, x 6i. 



