NO. 1701. SORTHWEfiT PACIFIC ISOPODS^RICHARDSON. 95 



Family LIMNORIID.^. 



Genus LIMNORIA Leach. 



LIMNORIA JAPONICA, new species. 



Body oblong-ovate, 2 mm. : 5 mm. Color of body, in alcohol, yellow, 

 with the fifth, sixth and seventh segments of the thorax reddish 

 brown. 



Head three times wider than long (| mm. : 1| mm.). Front with 

 a ronnded excavation. Eyes large, round, composite, and situated 

 close to the lateral margin. The head is very bulbous, and from the 

 anterior margin projects upward to form a large rounded prominence. 

 The first pair of antennae are composed of four articles; the first two 

 are subequal; the third is a little longer than either of the preceding; 

 the fourth is minute and terminates in a bunch of long hairs. The 

 second antenna? have a peduncle of five articles, the first two of which 

 are short, the last three longer and subequal; the flagellum is com- 

 posed of about five articles, and is furnished with a few hairs. 



The first segment of the thorax is twice as long as the head or any 

 of the six following segments, which are subequal. Epimera are dis- 

 tinctly separated on all the segments witli the 

 exception of the first and are in the form of wide 

 plates, gradually becoming Avider from the first 

 to the last. 



The first four segments of the abdomen are 

 subequal in length, and each is a little shorter 

 than any of the preceding six thoracic segments. 

 The fifth segment is twice as long as any of p j a 21.— limnokia 

 the four i^receding segments and has two low me- japonica. abdo- 



... . . MEN. X 15a. 



dian tubercles in longitudinal series. The sixth 

 or terminal segment is large, almost circular in outline, and con- 

 cave on the dorsal surface. It has a large prominent tubercle in 

 the median line near the base, and two j^rominent tubercles, close 

 together, one on either side of the median line, about one-third the 

 distance between the anterior and the posterior margin. These 

 tubercles are continued in two Ioav parallel ridges. The uropoda are 

 about as long as the abdomen; the inner branch is shorter than the 

 peduncle; the outer is minute. 



Thirty-one specimens of this species were collected at station 4828, 

 on the way from Nanao, Hondo, Japan, to Isuruga, Hondo, Japan, 

 at Sudzu Misaki Light, N. 57° W., 16 miles (lat. 37° 23' N.; long. 

 137° 3G' E.) at a depth of 163 fathoms. They were taken " from 

 crevices in water-logged fragment of bamboo." (H. Heath.) 



This species differs from Limnoria lignorum Rathke in having the 

 fifth abdominal segment armed with two low tubercles: in having 

 the terminal abdominal segment armed with three tubercles and two 



