344 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



The Northern Holiday Expedition of the Scripps Institution of Ocean- 

 ography, August and September 1951. (3) Cruises of the United 

 States Fisheries steamer Albatross in the northern Pacific. (4) Cruises 

 of the U.S.S. Burton Island to the Chukchi and Beaufort Seas during 

 August 1950 and August and September 1951, and to Amundsen Gulf 

 and Prince of Wales Strait during August 1953. (5) Northern Pacific 

 stations of cruise VII of the Carnegie, 1928-29. (6) Samples from 

 Japanese waters, sent to me by Dr. Sigeru Motoda and Mr. Zinziro 

 Nakai. (7) Samples from Korean waters provided by Mr. Won Tack 

 Yang. 



Five species of Parathemisto were obtained from these collections. 

 Each species is considered separately below with respect to its tax- 

 onomy, distribution, and ecolog} 7 . A sixth species, doubtfully identi- 

 fied from the Yellow Sea by Yamada, is also considered. 



Much of the work reported herein was carried out under the super- 

 vision of Dr. Martin W. Johnson, Scripps Institution of Oceanography, 

 to whom I am grateful for many valuable suggestions and for for- 

 warding to me the amphipods from the 1951 Burton Island Cruise. 

 Dr. Robert Bieri, Antioch College, kindly sent me the amphipods from 

 the 1953 Burton Island Cruise. I also wish to thank Dr. Sigeru 

 Motoda, Hokkaido University, and Mr. Zinziro Nakai, Tokai Re- 

 gional Research Laboratory, for sending me specimens of Parathemisto 

 from Japanese waters. Mr. Won Tack Yang, Central Fisheries Ex- 

 periment Station, Pusan, obligingly sent me specimens from several 

 localities around Korea. Dr. Isabella Gordon, British Museum (Nat- 

 ural History), made it possible for me to examine Challenger specimens 

 of Parathemisto pacifica Stebbing. 



Genus Parathemisto Boeck 



Themisto Guerin, 1825, p. 772.— Stephensen, 1923, p. 19; 1924, p. 94. 

 Parathemisto Boeck, 1870, p. 87.— Bovallius, 1889, p. 248.— Barnard, 1930, p. 419. 

 Euthemisto Bovallius, 1887, p. 21; 1889, p. 275. 



diagnosis (family characters omitted): Head moderately large, 

 globular. Pi (pereopod 1) simple. P2 chelate; carpal process narrow, 

 concave on anterior margin. Carpus of P3 and P4 more or less di- 

 lated, forming a prehensile organ with propodus. P5-7 longer than 

 P3 and P4. Uropods narrow, elongate. Type species, by monotypy, 

 Themisto gaudichaudii Guerin. 



In 1870 Boeck established the genus Parathemisto, which was to be 

 distinguished from Themisto Guerin by P5 not being much longer than 

 P6 or P7. Noting that Themisto had been preoccupied in 1815 by a 

 nudibranch mollusk, Bovallius (1887) changed the amphipod name to 

 Euthemisto. Stephensen (1924) combined the two genera, since the 

 relative lengths of P5-7 of the male of Themisto gracilipes Norman 



