NO. 1189. 



A NEW SPECIES OF JDOTEA—BICHABBSON. 



133 



The abdomen (including the terminal segment) is composed of three 

 segments, with suture lines indicative of another partly coalesced seg- 

 ment. The terminal segment, with sides slightly converging, has the 



Fig. 5.— a, abdomen of Idotea japonica ; h, abdomen of Idotea ochotensis ; c, abdomen of 

 Idotea EECTILINEATA. X 8. 



apex triangulate and produced much beyond the lateral angles, which 

 are roundly obtuse. 



The legs are slender. 



Two specimens come from Hakodate Bay, Japan ; depth, 8 fathoms in 

 gravel. 



Type.— No. 9348, U.S.N.M. 



This species differs from I. ocJiotensis Brandt in the following points: 



1. The proportions of the body. I. 

 ocJiotensis is stouter and shorter, the 

 relative proportion of breadth and 

 length being 2:7, while in I. japonica 

 the body is longer and narrower, the 

 relative proportion being 2 :10. 



2. The proportionately greater 

 length of the second pair of antennae.^ 



In I. ochotensis the joints of both 

 the peduncle and the flagellum are 

 stouter and shorter and the antennae 

 extend only to the j)osterior margin 

 of the third thoracic segment or the 

 middle of the fourth thoracic segment, 

 while in I. japonica these joints are 



longer and more slender, and the antennae reach the middle of the fifth 

 thoracic segment. 



1 Althougli there is some variation in the length of the second pair of antennae of 

 Idotea ochotensis, nevertheless tbese antenuie are always shorter than those of Idotea 

 japonica in specimens of the same size, and the peduncle of the antennas is also 

 shorter. 



Fig. 6. — a, leg of second pair of Idotea 



JAPONICA ; 6, LEG OF SECOND PAIR OF IDOTEA 



ochotensis. X 10. 



