I80PODS OF NORTH AMERICA. 



359 



but extend fully to the middle on the fourth segment. The epimera 

 of the fifth segment do not quite reach the posterior margin, but 

 extend about three-fourths the length of the segment. The epimera 

 of the last two segments extend the entire length of the segments. 



The abdomen is composed of three segments, two short ones ante- 

 rior to the terminal segment, which has suture lines on either side indi- 

 cating another partly coalesced segment. The terminal segment is 

 quadrangular with sides nearly parallel. The post-lateral angles am 

 prominent, and are separated by a shallow emargination from the 

 triangular middle portion, which is somewhat acutely produced in 

 the middle. 



The legs are all similar in structure. 



This description is made from specimens sent me by Dr. Walter 

 Faxon, from the Museum of Comparative Zoology at Harvard Uni- 

 versity. They were presented by Dr. Alexander Agassiz and are 

 marked Idothea urotoma Stimpson in Stimpson's handwriting. 



IDOTHEA FEWKESI, new species. 



Body narrow, elongate, about five and a half times longer than 

 wide, 71 mm. : 42 mm. 



Head one and a half times wider tha"h long, -i mm. : 6 mm. ; with the 

 anterior margin excavate in the middle between the antero-lateral 

 angles. The eyes are small, composite, about 

 twice as wide as long, and situated at the sides 

 of the head, halfway between the anterior and 

 posterior margins. The first pair of antennae 

 have the basal article greatly dilated; the second 

 and third articles are subequal, and each is 

 half as wide as the basal article and a little 

 shorter; the fourth article is clavate, and a 

 little longer than the third. The first pair of 

 antennae extend to the end of the second 

 article of the peduncle of the second pair of 

 antenna?. The basal article of the second 

 antennae is short, the second and third articles 

 are subequal, each being 2 mm. in length; 

 the fourth and fifth are subequal, each being 

 4 mm. in length, or twice as long as either 

 the second or the third article. The fla- 

 gelkim is composed of sixteen articles and is 

 10 mm. long. When retracted, the second 

 antennae extend to the posterior margin of 



the fourth thoracic segment. They are about half as long as the 

 body. The palp of the maxillipeds is composed of four articles. 



The first segment of the thorax is a little shorter in the dorsal 

 median line than any of the others^ being 2 mm. long. The antero- 



FIG. 387. IDOTHEA FEWKESI. 



