1897.] NATURAL SCIENCES OF PHILADELPHIA. 389 



A REVISION OF THE GENUS SYNIDOTEA.* 

 BY JAMES E. BENEDICT, PH.D. 



Among the unnamed Isopods in the National Museum seven spe- 

 cies regarded as new have been referred to Synidotea as defined by 

 Harger. Of the eight described species of the genus, five were in 

 the collection and an additional one was loaned by the California 

 Academy of Sciences. With so many new, and six of the eight de- 

 scribed species at hand, it was thought best to treat the genus mono- 

 graphically, and the descriptions of the two remaining species were 

 added. 



The new species all come from the North Pacific Ocean and Ber- 

 ing Sea. One was taken in San Francisco Bay by Mr. C. H. 

 Townsend while examining the oyster beds for the U. S. Fish Com- 

 mission ; the others were dredged by the ' Albatross,' one off the 

 State of Washington and five in Bering Sea ; two of the latter had, 

 however, previously been taken by Mr. W. H. Dall. 



The bathymetrical range of the genus is from shallow water to 

 695 fathoms. The geographical range is as follows : One species in 

 South African waters, one from Japan, one from Lower California, 

 two from California, one off the State of Washington, seven in Ber- 

 ing Sea and the adjacent waters of the Arctic Ocean, and two from 

 the North Atlantic. 



The genus Synidotea was instituted by Harger in 1878 to receive 

 Idotea bieuspida Owen and /. nodulosa Krjzfyer. The two species 

 now represent the two sections of the genus ; the bieuspida section 

 contains eleven and the nodulosa four species. All of the species 

 come well within the limits of the genus. 



The antennre of all have multi-articulate flagella. The palpus of 

 the maxillipeds has but three joints. The epimera of the four an- 

 terior segments are indicated, if at all, by a slight notch or pit in the 

 posterior margins midway between the lateral margins and the 

 median line ; the epimera of the three posterior segments are dis- 

 tinctly outlined in a dorsal view, and are solidly united to the true 



* Published by permission of the Secretary of the Smithsonian Institution. 

 26 



