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BULLETIN 2 01, UNITE© STATES NATIONAL MUSEUM 



fourth pleopod of the male for comparison with Ii's figures. I can 

 see no suture in the exopod of the fourth pleopod of the male and agree 

 that it appears to be single-jointed, though I have to confess that it is 

 exceedingly difficult to be quite definite on this point. 



Genus MYSIDIUM Dana 



Mysidia Dana, 1850, p. 130.— Zimmer, 1918, p. 24. 

 Macromysis Dana, 1852b, p. 638 (nee White, 1847, p. 81). 

 Mysidium Dana, 1852b, p. 638. 

 Diamysis Zimmer, 1915a, p. 214. 



The name Mysidia is preoccupied by a genus of Hemiptera founded 

 by Westwood in 1840, and there is no doubt that the later form of the 



Figure 95. — Paracanthomysis kurilensis Ii: a, Antennal scale, X 55; b, telson, X 55; c, 

 fourth pleopod of male, X 55. 



name, Mysidiwm, given by Dana in 1852, is the correct one for this 

 genus. 



Two species of the genus have been described, M. gracile (Dana) and 

 M. colwnbiae (Zimmer). A third species is herein described as new. 

 All three species are known only from American waters at present 

 and all are represented in the present material. They may be dis- 

 tinguished according to the key. 



