6'2 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVII. 



Immature specimens were found off Seal Islands, Alaska, on Necto- 

 cranqon alaHcenKis' off' Kootook Island. Alaska, on Crangon comnnunis; 

 north of Bird Islands, Shumagins, Alaska; Gulf of the Farallones, 

 California, on Cnnigon rugroinacnlata; Coal Harbor, Unga Island, on 

 Nectocrangon dentata; Captains Harbor, Unalaska, on Nectocrangon 

 dentata; Sanborn Harbor, Nagai, Shumagins on Nectocrangon lav; 

 Mazan Bay, Atka, on Nectocrangon, crassa; southwest of Hagemeister 

 Island, Alaska, on Nectocrangon alascensis,' northwest and northeast 

 of Unimak Island, Alaska, on Nectocrangon ala^scensis ,' Bering Sea, 

 between Pribilof Islands and Cape Newenham, on Nectocrangon lar; 

 Kouloulak .Ba3% Alaska, on Nectocrangon lar; between Bristol Bay 

 and Pribilof Islands, Alaska, on Nectocrangon lar; Arctic Ocean, on 

 Nectocrangon lar; Popoft* Straits, on Nectocrangon crassa; between 

 Bird and Nagai Islands, on Nectocrangon alascensis. 



List of CrangonidiP on which Argei(( jMigettensis is found parasitic: 



Nectocrantjon ovifer Rathbuu. 

 Nectocrangon lar (Owen). 

 Nectocrangon alascerms Kingsley. 

 Nectocrangon crassa Rathbun. 

 Nectocrangon dentata Rathbun. 

 Crangon nigromaculata Lockington. 

 Crangon. franciscorum angustimana Rath- 

 bun. 



Crangon dalli Rathbun. 

 Crangon communis Rathbun. 

 Crangon prophvpia Stimpson. 

 Crangon nigricauda Stimpson. 

 Crangon alascensis Lockington. 

 Crangon alascensis elongafn Rathl)un. 

 Crangon alba Holmes. 

 Crangon munita Dana. 



I/n//Mtare/ornis. — A female (probably in the first post-larval stage) 

 has the thoracic processes well developed, sometimes only on one side. 

 Inner pleopoda of the lirst pair usually present; all the outer pleopoda, 



the other four inner pleopoda and 

 the uropoda are not developed at 

 this stage. Marsupial plates are 

 small and just developing. Male 

 is similar to male found on adult 

 female. 



Immature female of a more 

 advanced stage has thoracic proc- 

 esses well developed, although 

 perhaps not quite as long as in 

 the preceding stage. Outer ple- 

 ^ ^"^ opoda and uropoda small, but all 



developed. The ffrst two inner pleopoda are present; the other three 

 may or may not be present. When present they are usually smaller 

 than the first two, decreasing in size to the fffth pair, and sometimes 

 difficult to discern. The marsupial plates are larger than in the pre- 

 ceding stage, but not fully developed. The incubatory pouch never 

 carries eggs in either of these stages. The male is similar to the male 

 of the adult female. 



Specimens of both immature stages were found on the same species 

 and genera of host as the adult females. 



Fig. 38.— Argeia pugettensis. a, borsal view of 



IMMATl'RE FEMALE: J>, VENTRAL VIEW OF SAME. 



