IS()I»ODS OF NORTH AMERICA. 



359 



but extend fully to the middle on the fourth sei4incnt. The epiniera 

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

 extend about thi-ee-fourths the length of the segment. The epiniera 

 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 are 

 pi-ominent, and are separated by a shallow emargination fi'om the 

 triangular middle })ortion, which is somewhat acutely produced in 

 the middle. 



The legs are all similar in structui'(\ 



This description is made from specimens sent me by Dr. \Valter 

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

 versit3\ The}' were presented by Dr. Alexander Agassiz and are 

 marked Idothea urotonui Stimpson in Stimpson's handwriting. 



IDOTHEA FEWKESI, new species. 



Body narrow, elongate, al)()ut ti\e and a half tinies longer than 

 wide, 7^ nun. : 42 mm. 



Head one and a half times wider than long, ^ mm. : <> nun.; with the 

 anterior margin excavate in the middle between the antero-lateral 

 angles. The eyes are small, composite, about 

 twice as wid(» as long, and situated at the sides 

 of the head, halfway between the anterior and 

 posterior margins. The first pair of antenna^ 

 have th(^ ])asal aiticle greatly dilated; the second 

 and third articles are su))e(jual, and each is 

 half as wdde as the basal article and a little 

 shorter; the fourth article is clavate, and a 

 little longer than the thii'd. The tii-st pair of 

 antennae extend to the end of the second 

 article of the peduncle of the second pair of 

 antennse. The l)asal article of the second 

 antenna is .short, the s(>cOnd and third articles 

 are subequal, <nich l)eing 2 nun. in length; 

 the fourth and tifth are .subequal. each being 

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

 the vsecond or the third article. The fla- 

 gelUun is composed of .sixteen articles and is 

 lo nun. long. When retracted, the second 

 antenna" extend to the posterior margin of 

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

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



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

 median line than an}^ of the others, being 2^ mm. long. The antero- 



FlG. 387. — lDOTHE.\ FEWKESI. 



X 3. 



