DESCRIPTION OF A NEW SPECIES OF IDOTEA FEOM 

 HAKODATE BAY, JAPAK 



By Harriet Richardson. 



Two distinct species were included by Miers^ with Idotea ochotensis 

 Brandt. In a former paper ^ the author has endeavored to define the 

 limits of Idotea ochotensis on tbe one side by preserving the specific 

 distinctions of Idotea rectilineata Lockington. It is the object of the 

 present paper to further define the limits of Idotea ochotensis on the 

 other side by showing the specific difierences of another species, for- 

 merly included. Two specimens from Hakodate Bay, Japan, in the 

 collection in the U. S. National Museum, when compared with a large 

 series of I. ochotensis from various localities, extending all the way 

 from Kamchatka to Bering Sea and the Aleutian Islands, confirms the 

 impossibility of uniting them with I. ochotensis. The specimen which 

 Miers saw in the British Museum collection from Yeddo Island, and 

 which he figures, undoubtedly belongs to the same species as our two 

 specimens from Hakodate Bay. In regard to it Miers says: 



It differs from Brandt's figure of /. ochotensis only in its relatively longer and 

 slenderer body and somewhat shorter antennse, which when retracted would not 

 reach to the posterior margin of the fourth thoracic segment, hut whose pedun- 

 cular joints are longer than in Brandt's figure. 



Further on he speaks of the tooth at the distal extremity of the 

 terminal segment as being very prominent in tbe specimen from 

 Japan. It is probable that Miers had specimens of all three species, 

 the one spoken of obtained at Vancouver Island being /. rectilineata 

 Lockington, the specimen from British Columbia being I. ochotensis 

 Brandt, and the Japanese specimen the one herein described. 



In comparing the species, specimens have been selected which are of 

 nearly the same size, in order to better compare the corresponding 

 parts. 



1 Journal Linn^an Society of London, XVI, 1883, pp. 32-34, pi. i, figs. 8-10. 

 2Proc. U. S. Nat. Mus., XXI, 1899, p. 845. 



Proceedings U. S. National Museum, Vol. XXII— No. 1 189. 



131 



