NO. 1701. X0RTHWE8T PACIFIC ISOPODS— RICHARDSON. 113 



partly coalesced segment at the base. The abdomen tapers to the 

 extremity, which has a deep rounded notch or excavation. 



Only one specimen comes from station 4987, on the way from 

 Hakodate, Hokkaido, Japan, to Otaru, Hokkaido, Japan, by way of 

 Tsugaru Strait, at Kamoi Mizaki Light, N. 76° E., 3.2 miles (lat. 43° 

 19' 20" N.; long. 140° 17' E.), at a depth of 59 fathoms in a rocky 

 bottom. 



This species differs from all the other species of Synidotea in the 

 presence of distinct epimera on the first thoracic segment. 



Type-specimen.— Cat. No. 39518, U.S.N.M. 



SYNIDOTEA TUBERCULATA, new species. 



Body oblong-ovate, about twice as long as wide (8| mm. ; 16^ mm.). 

 Head with the front excavate in the middle, on either side of which 

 the frontal border is wide and forms an angle with the lateral por- 

 tion. This angle is elevated in the form of an 

 arched tubercle. Just back of the median exca- 

 vation are two large, prominent tubercles, one on 

 either side of the median line. Posterior to these 

 two tubercles is a transverse row of six low 

 tubercles, three on either side of the median line. 

 Posterior to these six tubercles is a ridge wdiich is 

 elevated to form three low tubercles, one median 

 and one on either side of it. The eyes are large, 

 round, composite, and situated close to the lateral 

 margin on the posterior half of the head ; they are 

 somewhat elevated on rounded lobes. The first 

 pair of antennas have the first two articles sub- ^^^- 35.— synidotea 



^ ,.111 TUBERCULATA. X 2J. 



equal; the third and fourth are also about equal 

 in length and each is a little longer than either of the first two. The 

 first antennae extend to the end of the fourth article of the peduncle 

 of the second antennae. The first two articles of the second pair of 

 antenna^ are short and subequal ; the third is as long as the first two 

 taken together ; the fourth is a little longer than the third ; the fifth 

 is a little longer than the fourth ; the flagellum consists of thirteen 

 articles. "WTien retracted, the second antenna? extend to the posterior 

 margin of the second thoracic segment. All the epimera are firmly 

 united with the segments. 



The first four segments of the thorax are longer than the last three, 

 which gradually decrease a little in length. The first segment has a 

 prominent median tubercle, and a prominent arched, hornlike tubercle 

 on either side of the median tubercle. The second, third, and fourth 

 segments have each a median tubercle, and on either side of it a group 

 of five or six tubercles, two of the group being larger and more con- 



Proc.N.M.vol.37— 09— 8 



