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PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol. 37. 



long as the first three taken together; the flagellum is composed 

 of twenty-eight or twenty-nine articles. The second antennae, when 

 retracted, extend to the middle of the sixth thoracic segment. The 

 frontal lamina is large, triangular in front, wedge-shaped, with 

 the post-lateral angles produced and widely separating the basal 

 articles of the second pair of antennae. First, fifth, and sixth segments 

 longest, and subequal, each being 4 mm. in length. Second, third, 

 and seventh segments 3 mm. each in length; fourth segment 3^- mm. 

 long. The segments increase gradually in width to the fifth, which 

 is the widest ; the sixth and seventh decrease in width gradually, the 

 seventh being 12^ mm. wide. Epimera are distinctly separated on 

 all the segments with the exception of the first; they are broad 

 plates, with the posterior extremities rounded. 



The abdomen is abruptly narrower than the thorax, the basal seg- 

 ment being only 8 mm. wide. All six segments are distinct; the first 

 is mm. long; the four following segments are 2 mm. in length. 

 The post-lateral angles are acute and in the fifth segment are some- 

 what produced. The fifth segment also has the posterior margin 

 produced backward in a sharp, median point, about 1 mm. long. The 

 sixth or terminal segment is 7J mm. wide and 10 mm. long; it is 

 widely rounded posteriorly. The uropoda are about as long as the 

 terminal segment; the inner branch is a little longer and a little 

 wider than the outer branch; they are similar in shape and widely 

 rounded posteriorly. 



The first three pairs of legs are prehensile, the last four pairs 

 ambulatory. The last four pairs gradually increase in length, the two 

 last pairs being extremely long. The legs are all free from spines. 



One large specimen, a female, comes from station 4907, 10-20 miles 

 southwest of Koshika Islands, Eastern Sea, at Tsurikake Saki Light, 

 S. 83° E., 14.7 miles (lat. 31° 39' 30" N. ; long. 129° 24' E.) . Another 

 small specimen, a young female, comes from station 4906, Tsurikake 

 Saki Light, S. 85° E., 17.2 miles (lat. 31° 39' N. ; long. 129° 20' 30" 

 E.). They were taken at a depth of 406 fathoms in gray globigerina 

 ooze. 



This species differs from Syscenus infelix Harger in the much 

 broader and more ovate thorax, in the narrower abdomen, the longer 

 antennae and antennulae, in the differently shaped head, terminal 

 segment, and uropods, the broader frontal lamina, and the longer 

 legs. The fifth abdominal segment also has a median point on the 

 posterior margin produced backward, not found in S, infelix. 



Type-specimen.— Cat. No. 39502, U.S.N.M. 



