NO. 1701. X0RTHWE8T PACIFIC ISOPODS—RICHARDSON. Ill 



I 



SYNIDOTEA ACUTA, new species. 



Body oblong-ovate, about twice as long as wide, 5 mm. : 12 mm. 

 Color yellow, with the exception of the third and fourth segments, 

 which are red. 



Head with the front produced in a wide border on either side of a 

 median cleft. The frontal excavation is slight. The lateral portions 

 of the frontal border form an angle with the dorsal portion. Just 

 behind the median cleft is a prominent median tubercle. The eyes 

 are small, round, composite, and placed close to the lateral margins. 

 The first i)air of antennse extend to the middle of the fourth article 

 of the j^eduncle of the second pair of antennae; the first two articles 

 are about equal in length; the third and fourth are about equal in 

 length and each is a little longer than the second article. The second 

 pair of antenuffi have the first two articles about equal in length; 

 the third and fourth are also equal in length 

 and each is twice as long as either of the two 

 preceding articles; the fifth article is about one 

 and a half times longer than the fourth; the 

 flagellum consists of ten articles. When retracted 

 the second antennae extend to the posterior margin 

 of the first thoracic segment. 



The lateral margins of the first and second 

 thoracic segments are angulate; those of the fol- 

 lowing five segments are straight. All the epimera 

 are coalesced with the segments. The first four 

 segments are about equal in length; the last three 

 gradually decrease a little in length. 



The abdomen is composed of a single segment, 

 with a suture line on either side at the base, indi- 

 cating another partly coalesced segment. This segment is trian- 

 gulate, with the apex very slightly excavate. 



Only one specimen was collected b}^ the U. S. Bureau of Fisheries 

 Steamer Albatross at station 4778, on " Petrel Bank," Bering Sea, at 

 Semisopochnoi Island, r. t. S. 45° W., 1. t. S. 12° AV., about 12 miles 

 (lat. 52° 12' N.; long. 170° 52' E.) at a depth of 43 fathoms, in fine 

 black gravel. 



Type-specimen. — Cat. No. 39517, U.S.N.M. 



This species is very close to Sytiidotea hie usp Ida (Owen), but differs 

 in having the first two segments of the thorax with lateral margins 

 angulate, in having a prominent median tubercle on the head, and in 

 the shape of the frontal border. The abdomen is also different, in 

 being as long as wide, while in S. hicuspida it is wider than long, and 

 in having a more shallow excavation at the extremity. The second 

 antenna3 are also shorter, with fewer articles in the flagellum. 



